🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Security

Addressed high-severity security issues. Impact was limited to specific use cases detailed in the accompanying advisories; overall user exposure was estimated to be marginal.

• Decompression-bomb safeguards of the streaming API were bypassed:

  1. When HTTPResponse.drain_conn() was called after the response had been read and decompressed partially. (Reported by @Cycloctane)
  2. During the second HTTPResponse.read(amt=N) or HTTPResponse.stream(amt=N) call when the response was decompressed using the official Brotli library. (Reported by @kimkou2024)

  See GHSA-mf9v-mfxr-j63j for details.

• HTTP pools created using ProxyManager.connection_from_url did not strip sensitive headers specified in Retry.remove_headers_on_redirect when redirecting to a different host. (GHSA-qccp-gfcp-xxvc reported by @christos-spearbit)

Deprecations and Removals

• Used FutureWarning instead of DeprecationWarning for better visibility of existing deprecation notices. Rescheduled the removal of deprecated features to version 3.0. (#3763)
• Removed support for end-of-life Python 3.9. (#3720)
• Removed support for end-of-life PyPy3.10. (#4979)
• Bumped the minimum supported pyOpenSSL version to 19.0.0. (#3777)

Bugfixes

• Fixed a bug where HTTPResponse.read(amt=None) was ignoring decompressed data buffered from previous partial reads. (#3636)
• Fixed a bug where HTTPResponse.read() could cache only part of the response after a partial read when cache_content=True. (#4967)
• Fixed HTTPResponse.stream() and HTTPResponse.read_chunked() to handle amt=0. (#3793)
• Updated _TYPE_BODY type alias to include missing Iterable[str], matching the documented and runtime behavior of chunked request bodies. (#3798)
• Fixed LocationParseError when paths resembling schemeless URIs were passed to HTTPConnectionPool.urlopen(). (#3352)
• Fixed BaseHTTPResponse.readinto() type annotation to accept memoryview in addition to bytearray, matching the io.RawIOBase.readinto contract and enabling use with io.BufferedReader without type errors. (#3764)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Fixed a security issue where decompression-bomb safeguards of the streaming API were bypassed when HTTP redirects were followed. (CVE-2026-21441 reported by @D47A, 8.9 High, GHSA-38jv-5279-wg99)
• Started treating Retry-After times greater than 6 hours as 6 hours by default. (#3743)
• Fixed urllib3.connection.VerifiedHTTPSConnection on Emscripten. (#3752)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Fixed HTTPResponse.read_chunked() to properly handle leftover data in the decoder's buffer when reading compressed chunked responses. (#3734)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Restore previously removed HTTPResponse.getheaders() and HTTPResponse.getheader() methods. (#3731)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Security

• Fixed a security issue where streaming API could improperly handle highly compressed HTTP content ("decompression bombs") leading to excessive resource consumption even when a small amount of data was requested. Reading small chunks of compressed data is safer and much more efficient now. (CVE-2025-66471 reported by @Cycloctane, 8.9 High, GHSA-2xpw-w6gg-jr37)
• Fixed a security issue where an attacker could compose an HTTP response with virtually unlimited links in the Content-Encoding header, potentially leading to a denial of service (DoS) attack by exhausting system resources during decoding. The number of allowed chained encodings is now limited to 5. (CVE-2025-66418 reported by @illia-v, 8.9 High, GHSA-gm62-xv2j-4w53)

Features

• Enabled retrieval, deletion, and membership testing in HTTPHeaderDict using bytes keys. (#3653)
• Added host and port information to string representations of HTTPConnection. (#3666)
• Added support for Python 3.14 free-threading builds explicitly. (#3696)

Removals

• Removed the HTTPResponse.getheaders() method in favor of HTTPResponse.headers. Removed the HTTPResponse.getheader(name, default) method in favor of HTTPResponse.headers.get(name, default). (#3622)

Bugfixes

• Fixed redirect handling in urllib3.PoolManager when an integer is passed for the retries parameter. (#3649)
• Fixed HTTPConnectionPool when used in Emscripten with no explicit port. (#3664)
• Fixed handling of SSLKEYLOGFILE with expandable variables. (#3700)

Misc

• Changed the zstd extra to install backports.zstd instead of zstandard on Python 3.13 and before. (#3693)
• Improved the performance of content decoding by optimizing BytesQueueBuffer class. (#3710)
• Allowed building the urllib3 package with newer setuptools-scm v9.x. (#3652)
• Ensured successful urllib3 builds by setting Hatchling requirement to ≥ 1.27.0. (#3638)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Security issues

urllib3 2.5.0 fixes two moderate security issues:

• Pool managers now properly control redirects when retries is passed — CVE-2025-50181 reported by @sandumjacob (5.3 Medium, GHSA-pq67-6m6q-mj2v)
• Redirects are now controlled by urllib3 in the Node.js runtime — CVE-2025-50182 (5.3 Medium, GHSA-48p4-8xcf-vxj5)

Features

• Added support for the compression.zstd module that is new in Python 3.14. See PEP 784 for more information. (#3610)
• Added support for version 0.5 of hatch-vcs (#3612)

Bugfixes

• Raised exception for HTTPResponse.shutdown on a connection already released to the pool. (#3581)
• Fixed incorrect CONNECT statement when using an IPv6 proxy with connection_from_host. Previously would not be wrapped in []. (#3615)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Features

• Applied PEP 639 by specifying the license fields in pyproject.toml. (#3522)
• Updated exceptions to save and restore more properties during the pickle/serialization process. (#3567)
• Added verify_flags option to create_urllib3_context with a default of VERIFY_X509_PARTIAL_CHAIN and VERIFY_X509_STRICT for Python 3.13+. (#3571)

Bugfixes

• Fixed a bug with partial reads of streaming data in Emscripten. (#3555)

Misc

• Switched to uv for installing development dependecies. (#3550)
• Removed the multiple.intoto.jsonl asset from GitHub releases. Attestation of release files since v2.3.0 can be found on PyPI. (#3566)

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Features

• Added HTTPResponse.shutdown() to stop any ongoing or future reads for a specific response. It calls shutdown(SHUT_RD) on the underlying socket. This feature was sponsored by LaunchDarkly. (#2868)
• Added support for JavaScript Promise Integration on Emscripten. This enables more efficient WebAssembly requests and streaming, and makes it possible to use in Node.js if you launch it as node --experimental-wasm-stack-switching. (#3400)
• Added the proxy_is_tunneling property to HTTPConnection and HTTPSConnection. (#3285)
• Added pickling support to NewConnectionError and NameResolutionError. (#3480)

Bugfixes

• Fixed an issue in debug logs where the HTTP version was rendering as "HTTP/11" instead of "HTTP/1.1". (#3489)

Deprecations and Removals

• Removed support for Python 3.8. (#3492)

Full Changelog: 2.2.3...2.3.0

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Features

• Added support for Python 3.13. (#3473)

Bugfixes

• Fixed the default encoding of chunked request bodies to be UTF-8 instead of ISO-8859-1. All other methods of supplying a request body already use UTF-8 starting in urllib3 v2.0. (#3053)
• Fixed ResourceWarning on CONNECT with Python < 3.11.4 by backporting python/cpython#103472. (`#3252)
• Adjust tolerance for floating-point comparison on Windows to avoid flakiness in CI (#3413)
• Fixed a crash where certain standard library hash functions were absent in restricted environments. (#3432)
• Fixed mypy error when adding to HTTPConnection.default_socket_options. (#3448)

HTTP/2 (experimental)

HTTP/2 support is still in early development.

• Excluded Transfer-Encoding: chunked from HTTP/2 request body (#3425)
• Added version checking for h2 (https://pypi.org/project/h2/) usage. Now only accepting supported h2 major version 4.x.x. (#3290)
• Added a probing mechanism for determining whether a given target origin supports HTTP/2 via ALPN. (#3301)
• Add support for sending a request body with HTTP/2 (#3302)

Full Changelog: 2.2.2...2.2.3

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Added the Proxy-Authorization header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via Retry.remove_headers_on_redirect.
• Allowed passing negative integers as amt to read methods of http.client.HTTPResponse as an alternative to None. (#3122)
• Fixed return types representing copying actions to use typing.Self. (#3363)

Full Changelog: https://github.com/urllib3/urllib3/compare/2.2.1...2.2.2

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Fixed issue where InsecureRequestWarning was emitted for HTTPS connections when using Emscripten. (#3331)
• Fixed HTTPConnectionPool.urlopen to stop automatically casting non-proxy headers to HTTPHeaderDict. This change was premature as it did not apply to proxy headers and HTTPHeaderDict does not handle byte header values correctly yet. (#3343)
• Changed ProtocolError to InvalidChunkLength when response terminates before the chunk length is sent. (#2860)
• Changed ProtocolError to be more verbose on incomplete reads with excess content. (#3261)

🖥️ urllib3 now works in the browser

:tada: This release adds experimental support for using urllib3 in the browser with Pyodide! :tada:

Thanks to Joe Marshall (@joemarshall) for contributing this feature. This change was possible thanks to work done in urllib3 v2.0 to detach our API from http.client. Please report all bugs to the urllib3 issue tracker.

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Added support for Emscripten and Pyodide, including streaming support in cross-origin isolated browser environments where threading is enabled. (#2951)
• Added support for HTTPResponse.read1() method. (#3186)
• Added rudimentary support for HTTP/2. (#3284)
• Fixed issue where requests against urls with trailing dots were failing due to SSL errors when using proxy. (#2244)
• Fixed HTTPConnection.proxy_is_verified and HTTPSConnection.proxy_is_verified to be always set to a boolean after connecting to a proxy. It could be None in some cases previously. (#3130)
• Fixed an issue where headers passed in a request with json= would be mutated (#3203)
• Fixed HTTPSConnection.is_verified to be set to False when connecting from a HTTPS proxy to an HTTP target. It was set to True previously. (#3267)
• Fixed handling of new error message from OpenSSL 3.2.0 when configuring an HTTP proxy as HTTPS (#3268)
• Fixed TLS 1.3 post-handshake auth when the server certificate validation is disabled (#3325)

Note for downstream distributors: To run integration tests, you now need to run the tests a second time with the --integration pytest flag. (#3181)

Read the v2 migration guide for help upgrading to the latest version of urllib3.

Removals

• Removed support for the deprecated urllib3[secure] extra. (#2680)
• Removed support for the deprecated SecureTransport TLS implementation. (#2681)
• Removed support for the end-of-life Python 3.7. (#3143)

Bugfixes

• Allowed loading CA certificates from memory for proxies. (#3065)
• Fixed decoding Gzip-encoded responses which specified x-gzip content-encoding. (#3174)

• Made body stripped from HTTP requests changing the request method to GET after HTTP 303 "See Other" redirect responses. (GHSA-g4mx-q9vg-27p4)

• Added the Cookie header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via Retry.remove_headers_on_redirect. (GHSA-v845-jxx5-vc9f)

• Allowed pyOpenSSL third-party module without any deprecation warning. #3126
• Fixed default blocksize of HTTPConnection classes to match high-level classes. Previously was 8KiB, now 16KiB. #3066

• Added support for union operators to HTTPHeaderDict (#2254)
• Added BaseHTTPResponse to urllib3.__all__ (#3078)
• Fixed urllib3.connection.HTTPConnection to raise the http.client.connect audit event to have the same behavior as the standard library HTTP client (#2757)
• Relied on the standard library for checking hostnames in supported PyPy releases (#3087)

• Allowed alternative SSL libraries such as LibreSSL, while still issuing a warning as we cannot help users facing issues with implementations other than OpenSSL. #3020
• Deprecated URLs which don't have an explicit scheme #2950
• Fixed response decoding with Zstandard when compressed data is made of several frames. #3008
• Fixed assert_hostname=False to correctly skip hostname check. #3051

• Fixed HTTPResponse.stream() to continue yielding bytes if buffered decompressed data was still available to be read even if the underlying socket is closed. This prevents a compressed response from being truncated. (https://github.com/urllib3/urllib3/issues/3009)

• Fixed a socket leak when fingerprint or hostname verifications fail. (#2991)
• Fixed an error when HTTPResponse.read(0) was the first read call or when the internal response body buffer was otherwise empty. (#2998)

Read the v2.0 migration guide for help upgrading to the latest version of urllib3.

Removed

• Removed support for Python 2.7, 3.5, and 3.6 (#883, #2336).
• Removed fallback on certificate commonName in match_hostname() function. This behavior was deprecated in May 2000 in RFC 2818. Instead only subjectAltName is used to verify the hostname by default. To enable verifying the hostname against commonName use SSLContext.hostname_checks_common_name = True (#2113).
• Removed support for Python with an ssl module compiled with LibreSSL, CiscoSSL, wolfSSL, and all other OpenSSL alternatives. Python is moving to require OpenSSL with PEP 644 (#2168).
• Removed support for OpenSSL versions earlier than 1.1.1 or that don't have SNI support. When an incompatible OpenSSL version is detected an ImportError is raised (#2168).
• Removed the list of default ciphers for OpenSSL 1.1.1+ and SecureTransport as their own defaults are already secure (#2082).
• Removed urllib3.contrib.appengine.AppEngineManager and support for Google App Engine Standard Environment (#2044).
• Removed deprecated Retry options method_whitelist, DEFAULT_REDIRECT_HEADERS_BLACKLIST (#2086).
• Removed urllib3.HTTPResponse.from_httplib (#2648).
• Removed default value of None for the request_context parameter of urllib3.PoolManager.connection_from_pool_key. This change should have no effect on users as the default value of None was an invalid option and was never used (#1897).
• Removed the urllib3.request module. urllib3.request.RequestMethods has been made a private API. This change was made to ensure that from urllib3 import request imported the top-level request() function instead of the urllib3.request module (#2269).
• Removed support for SSLv3.0 from the urllib3.contrib.pyopenssl even when support is available from the compiled OpenSSL library (#2233).
• Removed the deprecated urllib3.contrib.ntlmpool module (#2339).
• Removed DEFAULT_CIPHERS, HAS_SNI, USE_DEFAULT_SSLCONTEXT_CIPHERS, from the private module urllib3.util.ssl_ (#2168).
• Removed urllib3.exceptions.SNIMissingWarning (#2168).
• Removed the _prepare_conn method from HTTPConnectionPool. Previously this was only used to call HTTPSConnection.set_cert() by HTTPSConnectionPool (#1985).
• Removed tls_in_tls_required property from HTTPSConnection. This is now determined from the scheme parameter in HTTPConnection.set_tunnel() (#1985).

Deprecated

• Deprecated HTTPResponse.getheaders() and HTTPResponse.getheader() which will be removed in urllib3 v2.1.0. Instead use HTTPResponse.headers and HTTPResponse.headers.get(name, default). (#1543, #2814).
• Deprecated urllib3.contrib.pyopenssl module which will be removed in urllib3 v2.1.0 (#2691).
• Deprecated urllib3.contrib.securetransport module which will be removed in urllib3 v2.1.0 (#2692).
• Deprecated ssl_version option in favor of ssl_minimum_version. ssl_version will be removed in urllib3 v2.1.0 (#2110).
• Deprecated the strict parameter as it's not longer needed in Python 3.x. It will be removed in urllib3 v2.1.0 (#2267)
• Deprecated the NewConnectionError.pool attribute which will be removed in urllib3 v2.1.0 (#2271).
• Deprecated format_header_param_html5 and format_header_param in favor of format_multipart_header_param (#2257).
• Deprecated RequestField.header_formatter parameter which will be removed in urllib3 v2.1.0 (#2257).
• Deprecated HTTPSConnection.set_cert() method. Instead pass parameters to the HTTPSConnection constructor (#1985).
• Deprecated HTTPConnection.request_chunked() method which will be removed in urllib3 v2.1.0. Instead pass chunked=True to HTTPConnection.request() (#1985).

Added

• Added top-level urllib3.request function which uses a preconfigured module-global PoolManager instance (#2150).
• Added the json parameter to urllib3.request(), PoolManager.request(), and ConnectionPool.request() methods to send JSON bodies in requests. Using this parameter will set the header Content-Type: application/json if Content-Type isn't already defined. Added support for parsing JSON response bodies with HTTPResponse.json() method (#2243).
• Added type hints to the urllib3 module (#1897).
• Added ssl_minimum_version and ssl_maximum_version options which set SSLContext.minimum_version and SSLContext.maximum_version (#2110).
• Added support for Zstandard (RFC 8878) when zstandard 1.18.0 or later is installed. Added the zstd extra which installs the zstandard package (#1992).
• Added urllib3.response.BaseHTTPResponse class. All future response classes will be subclasses of BaseHTTPResponse (#2083).
• Added FullPoolError which is raised when PoolManager(block=True) and a connection is returned to a full pool (#2197).
• Added HTTPHeaderDict to the top-level urllib3 namespace (#2216).
• Added support for configuring header merging behavior with HTTPHeaderDict When using a HTTPHeaderDict to provide headers for a request, by default duplicate header values will be repeated. But if combine=True is passed into a call to HTTPHeaderDict.add, then the added header value will be merged in with an existing value into a comma-separated list (X-My-Header: foo, bar) (#2242).
• Added NameResolutionError exception when a DNS error occurs (#2305).
• Added proxy_assert_hostname and proxy_assert_fingerprint kwargs to ProxyManager (#2409).
• Added a configurable backoff_max parameter to the Retry class. If a custom backoff_max is provided to the Retry class, it will replace the Retry.DEFAULT_BACKOFF_MAX (#2494).
• Added the authority property to the Url class as per RFC 3986 3.2. This property should be used in place of netloc for users who want to include the userinfo (auth) component of the URI (#2520).
• Added the scheme parameter to HTTPConnection.set_tunnel to configure the scheme of the origin being tunnelled to (#1985).
• Added the is_closed, is_connected and has_connected_to_proxy properties to HTTPConnection (#1985).
• Added optional backoff_jitter parameter to Retry. (#2952)

Changed

• Changed urllib3.response.HTTPResponse.read to respect the semantics of io.BufferedIOBase regardless of compression. Specifically, this method:
  • Only returns an empty bytes object to indicate EOF (that is, the response has been fully consumed).
  • Never returns more bytes than requested.
  • Can issue any number of system calls: zero, one or multiple. If you want each urllib3.response.HTTPResponse.read call to issue a single system call, you need to disable decompression by setting decode_content=False (#2128).
• Changed urllib3.HTTPConnection.getresponse to return an instance of urllib3.HTTPResponse instead of http.client.HTTPResponse (#2648).
• Changed ssl_version to instead set the corresponding SSLContext.minimum_version and SSLContext.maximum_version values. Regardless of ssl_version passed SSLContext objects are now constructed using ssl.PROTOCOL_TLS_CLIENT (#2110).
• Changed default SSLContext.minimum_version to be TLSVersion.TLSv1_2 in line with Python 3.10 (#2373).
• Changed ProxyError to wrap any connection error (timeout, TLS, DNS) that occurs when connecting to the proxy (#2482).
• Changed urllib3.util.create_urllib3_context to not override the system cipher suites with a default value. The new default will be cipher suites configured by the operating system (#2168).
• Changed multipart/form-data header parameter formatting matches the WHATWG HTML Standard as of 2021-06-10. Control characters in filenames are no longer percent encoded (#2257).
• Changed the error raised when connecting via HTTPS when the ssl module isn't available from SSLError to ImportError (#2589).
• Changed HTTPConnection.request() to always use lowercase chunk boundaries when sending requests with Transfer-Encoding: chunked (#2515).
• Changed enforce_content_length default to True, preventing silent data loss when reading streamed responses (#2514).
• Changed internal implementation of HTTPHeaderDict to use dict instead of collections.OrderedDict for better performance (#2080).
• Changed the urllib3.contrib.pyopenssl module to wrap OpenSSL.SSL.Error with ssl.SSLError in PyOpenSSLContext.load_cert_chain (#2628).
• Changed usage of the deprecated socket.error to OSError (#2120).
• Changed all parameters in the HTTPConnection and HTTPSConnection constructors to be keyword-only except host and port (#1985).
• Changed HTTPConnection.getresponse() to set the socket timeout from HTTPConnection.timeout value before reading data from the socket. This previously was done manually by the HTTPConnectionPool calling HTTPConnection.sock.settimeout(...) (#1985).
• Changed the _proxy_host property to _tunnel_host in HTTPConnectionPool to more closely match how the property is used (value in HTTPConnection.set_tunnel()) (#1985).
• Changed name of Retry.BACK0FF_MAX to be Retry.DEFAULT_BACKOFF_MAX.
• Changed TLS handshakes to use SSLContext.check_hostname when possible (#2452).
• Changed server_hostname to behave like other parameters only used by HTTPSConnectionPool (#2537).
• Changed the default blocksize to 16KB to match OpenSSL's default read amounts (#2348).
• Changed HTTPResponse.read() to raise an error when calling with decode_content=False after using decode_content=True to prevent data loss (#2800).

Fixed

• Fixed thread-safety issue where accessing a PoolManager with many distinct origins would cause connection pools to be closed while requests are in progress (#1252).
• Fixed an issue where an HTTPConnection instance would erroneously reuse the socket read timeout value from reading the previous response instead of a newly configured connect timeout. Instead now if HTTPConnection.timeout is updated before sending the next request the new timeout value will be used (#2645).
• Fixed socket.error.errno when raised from pyOpenSSL's OpenSSL.SSL.SysCallError (#2118).
• Fixed the default value of HTTPSConnection.socket_options to match HTTPConnection (#2213).
• Fixed a bug where headers would be modified by the remove_headers_on_redirect feature (#2272).
• Fixed a reference cycle bug in urllib3.util.connection.create_connection() (#2277).
• Fixed a socket leak if HTTPConnection.connect() fails (#2571).
• Fixed urllib3.contrib.pyopenssl.WrappedSocket and urllib3.contrib.securetransport.WrappedSocket close methods (#2970)

• Removed the setup.py shim, python setup.py install will print [Errno 2] No such file or directory instead of a warning to use pip (#2975)
• Added optional backoff_jitter parameter to Retry (#2952)
• Fixed URL encoding by removing '!' from the 'unreserved' character set specified in RFC 3986 (#2899)
• Fixed a sign error in a check for whether a character is in the ASCII range (#2901)
• Fixed urllib3.contrib.pyopenssl.WrappedSocket and urllib3.contrib.securetransport.WrappedSocket close methods (#2970)

Read the v2.0 migration guide for help upgrading to the latest version of urllib3.

• Fixed logging error when using add_stderr_logger (#2839)
• Fixed parsing of port 0 (zero) returning None, instead of 0 (#2850)
• Fixed the type hint of PoolKey.key_retries by adding bool to the union (#2865)

Read the v2.0 migration guide for help upgrading to the latest version of urllib3.

• Changed HTTPResponse.read() to raise an error when calling with decode_content=False after using decode_content=True to prevent data loss (https://github.com/urllib3/urllib3/issues/2800).
• Changed HTTPResponse.getheaders() and .getheader() to previous behavior in 1.26.x. Instead we are deprecating these methods in favor of HTTPResponse.headers.items() and HTTPResponse.headers.get(). Both deprecated methods will be removed in v2.1.0 (https://github.com/urllib3/urllib3/issues/2814)
• Fixed an issue where parsing a URL with leading zeroes in the port would be rejected even when the port number after removing the zeroes was valid. (https://github.com/urllib3/urllib3/pull/2806)
• Fixed deprecation warning when using cryptography v39.0.0. This fix requires using pyOpenSSL>=17.1.0 and cryptography>=1.9. (https://github.com/urllib3/urllib3/pull/2829)

Read the v2.0 migration guide for help upgrading to the latest version of urllib3!

Added

• Added type hints to the urllib3 module (#1897).
• Added ssl_minimum_version and ssl_maximum_version options which set SSLContext.minimum_version and SSLContext.maximum_version (#2110).
• Added support for Zstandard (RFC 8878) when zstandard 1.18.0 or later is installed. Added the zstd extra which installs the zstandard package (#1992).
• Added urllib3.response.BaseHTTPResponse class. All future response classes will be subclasses of BaseHTTPResponse (#2083).
• Added top-level urllib3.request function which uses a preconfigured module-global PoolManager instance (#2150).
• Added FullPoolError which is raised when PoolManager(block=True) and a connection is returned to a full pool (#2197).
• Added HTTPHeaderDict to the top-level urllib3 namespace (#2216).
• Added the json parameter to urllib3.request(), PoolManager.request(), and ConnectionPool.request() methods to send JSON bodies in requests. Using this parameter will set the header Content-Type: application/json if Content-Type isn't already defined. Added support for parsing JSON response bodies with HTTPResponse.json() method (#2243).
• Added support for configuring header merging behavior with HTTPHeaderDict When using a HTTPHeaderDict to provide headers for a request, by default duplicate header values will be repeated. But if combine=True is passed into a call to HTTPHeaderDict.add, then the added header value will be merged in with an existing value into a comma-separated list (X-My-Header: foo, bar) (#2242).
• Added NameResolutionError exception when a DNS error occurs (#2305).
• Added proxy_assert_hostname and proxy_assert_fingerprint kwargs to ProxyManager (#2409).
• Added a configurable backoff_max parameter to the Retry class. If a custom backoff_max is provided to the Retry class, it will replace the Retry.DEFAULT_BACKOFF_MAX (#2494).
• Added the authority property to the Url class as per RFC 3986 3.2. This property should be used in place of netloc for users who want to include the userinfo (auth) component of the URI (#2520).
• Added the scheme parameter to HTTPConnection.set_tunnel to configure the scheme of the origin being tunnelled to (#1985).
• Added the is_closed, is_connected and has_connected_to_proxy properties to HTTPConnection (#1985).

Removed

• Removed support for Python 2.7, 3.5, and 3.6 (#883, #2336).
• Removed fallback on certificate commonName in match_hostname() function. This behavior was deprecated in May 2000 in RFC 2818. Instead only subjectAltName is used to verify the hostname by default. To enable verifying the hostname against commonName use SSLContext.hostname_checks_common_name = True (#2113).
• Removed support for Python with an ssl module compiled with LibreSSL, CiscoSSL, wolfSSL, and all other OpenSSL alternatives. Python is moving to require OpenSSL with PEP 644 (#2168).
• Removed support for OpenSSL versions earlier than 1.1.1 or that don't have SNI support. When an incompatible OpenSSL version is detected an ImportError is raised (#2168).
• Removed the list of default ciphers for OpenSSL 1.1.1+ and SecureTransport as their own defaults are already secure (#2082).
• Removed urllib3.contrib.appengine.AppEngineManager and support for Google App Engine Standard Environment (#2044).
• Removed deprecated Retry options method_whitelist, DEFAULT_REDIRECT_HEADERS_BLACKLIST (#2086).
• Removed urllib3.HTTPResponse.from_httplib (#2648).
• Removed default value of None for the request_context parameter of urllib3.PoolManager.connection_from_pool_key. This change should have no effect on users as the default value of None was an invalid option and was never used (#1897).
• Removed the urllib3.request module. urllib3.request.RequestMethods has been made a private API. This change was made to ensure that from urllib3 import request imported the top-level request() function instead of the urllib3.request module (#2269).
• Removed support for SSLv3.0 from the urllib3.contrib.pyopenssl even when support is available from the compiled OpenSSL library (#2233).
• Removed the deprecated urllib3.contrib.ntlmpool module (#2339).
• Removed DEFAULT_CIPHERS, HAS_SNI, USE_DEFAULT_SSLCONTEXT_CIPHERS, from the private module urllib3.util.ssl_ (#2168).
• Removed urllib3.exceptions.SNIMissingWarning (#2168).
• Removed the _prepare_conn method from HTTPConnectionPool. Previously this was only used to call HTTPSConnection.set_cert() by HTTPSConnectionPool (#1985).
• Removed tls_in_tls_required property from HTTPSConnection. This is now determined from the scheme parameter in HTTPConnection.set_tunnel() (#1985).

Changed

• Changed urllib3.response.HTTPResponse.read to respect the semantics of io.BufferedIOBase regardless of compression. Specifically, this method:
  • Only returns an empty bytes object to indicate EOF (that is, the response has been fully consumed).
  • Never returns more bytes than requested.
  • Can issue any number of system calls: zero, one or multiple. If you want each urllib3.response.HTTPResponse.read call to issue a single system call, you need to disable decompression by setting decode_content=False (#2128).
• Changed ssl_version to instead set the corresponding SSLContext.minimum_version and SSLContext.maximum_version values. Regardless of ssl_version passed SSLContext objects are now constructed using ssl.PROTOCOL_TLS_CLIENT (#2110).
• Changed default SSLContext.minimum_version to be TLSVersion.TLSv1_2 in line with Python 3.10 (#2373).
• Changed ProxyError to wrap any connection error (timeout, TLS, DNS) that occurs when connecting to the proxy (#2482).
• Changed urllib3.util.create_urllib3_context to not override the system cipher suites with a default value. The new default will be cipher suites configured by the operating system (#2168).
• Changed multipart/form-data header parameter formatting matches the WHATWG HTML Standard as of 2021-06-10. Control characters in filenames are no longer percent encoded (#2257).
• Changed urllib3.HTTPConnection.getresponse to return an instance of urllib3.HTTPResponse instead of http.client.HTTPResponse (#2648).
• Changed return type of HTTPResponse.getheaders() method to return a list of key-value tuples to match CPython (#1543).
• Changed the error raised when connecting via HTTPS when the ssl module isn't available from SSLError to ImportError (#2589).
• Changed HTTPConnection.request() to always use lowercase chunk boundaries when sending requests with Transfer-Encoding: chunked (#2515).
• Changed enforce_content_length default to True, preventing silent data loss when reading streamed responses (#2514).
• Changed internal implementation of HTTPHeaderDict to use dict instead of collections.OrderedDict for better performance (#2080).
• Changed the urllib3.contrib.pyopenssl module to wrap OpenSSL.SSL.Error with ssl.SSLError in PyOpenSSLContext.load_cert_chain (#2628).
• Changed usage of the deprecated socket.error to OSError (#2120).
• Changed all parameters in the HTTPConnection and HTTPSConnection constructors to be keyword-only except host and port (#1985).
• Changed urllib3.util.is_connection_dropped() to use HTTPConnection.is_connected (#1985).
• Changed HTTPConnection.getresponse() to set the socket timeout from HTTPConnection.timeout value before reading data from the socket. This previously was done manually by the HTTPConnectionPool calling HTTPConnection.sock.settimeout(...) (#1985).
• Changed the _proxy_host property to _tunnel_host in HTTPConnectionPool to more closely match how the property is used (value in HTTPConnection.set_tunnel()) (#1985).
• Changed name of Retry.BACK0FF_MAX to be Retry.DEFAULT_BACKOFF_MAX.
• Changed TLS handshakes to use SSLContext.check_hostname when possible (#2452).
• Changed server_hostname to behave like other parameters only used by HTTPSConnectionPool (#2537).
• Changed the default blocksize to 16KB to match OpenSSL's default read amounts (#2348).

Deprecated

• Deprecated urllib3.contrib.pyopenssl module which will be removed in urllib3 v2.1.0 (#2691).
• Deprecated urllib3.contrib.securetransport module which will be removed in urllib3 v2.1.0 (#2692).
• Deprecated ssl_version option in favor of ssl_minimum_version. ssl_version will be removed in urllib3 v2.1.0 (#2110).
• Deprecated the strict parameter as it's not longer needed in Python 3.x. It will be removed in urllib3 v2.1.0 (#2267)
• Deprecated the NewConnectionError.pool attribute which will be removed in urllib3 v2.1.0 (#2271).
• Deprecated format_header_param_html5 and format_header_param in favor of format_multipart_header_param (#2257).
• Deprecated RequestField.header_formatter parameter which will be removed in urllib3 v2.1.0 (#2257).
• Deprecated HTTPSConnection.set_cert() method. Instead pass parameters to the HTTPSConnection constructor (#1985).
• Deprecated HTTPConnection.request_chunked() method which will be removed in urllib3 v2.1.0. Instead pass chunked=True to HTTPConnection.request() (#1985).

Fixed

• Fixed thread-safety issue where accessing a PoolManager with many distinct origins would cause connection pools to be closed while requests are in progress (#1252).
• Fixed an issue where an HTTPConnection instance would erroneously reuse the socket read timeout value from reading the previous response instead of a newly configured connect timeout. Instead now if HTTPConnection.timeout is updated before sending the next request the new timeout value will be used (#2645).
• Fixed socket.error.errno when raised from pyOpenSSL's OpenSSL.SSL.SysCallError (#2118).
• Fixed the default value of HTTPSConnection.socket_options to match HTTPConnection (#2213).
• Fixed a bug where headers would be modified by the remove_headers_on_redirect feature (#2272).
• Fixed a reference cycle bug in urllib3.util.connection.create_connection() (#2277).
• Fixed a socket leak if HTTPConnection.connect() fails (#2571).

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Fixed a crash where certain standard library hash functions were absent in FIPS-compliant environments. (#3432)
• Replaced deprecated dash-separated setuptools entries in setup.cfg. (#3461)
• Took into account macOS setting ECONNRESET instead of EPROTOTYPE in its newer versions. (#3416)
• Backported changes to our tests and CI configuration from v2.x to support testing with CPython 3.12 and 3.13. (#3436)

Full Changelog: 1.26.19...1.26.20

🚀 urllib3 is fundraising for HTTP/2 support

urllib3 is raising ~$40,000 USD to release HTTP/2 support and ensure long-term sustainable maintenance of the project after a sharp decline in financial support for 2023. If your company or organization uses Python and would benefit from HTTP/2 support in Requests, pip, cloud SDKs, and thousands of other projects please consider contributing financially to ensure HTTP/2 support is developed sustainably and maintained for the long-haul.

Thank you for your support.

Changes

• Added the Proxy-Authorization header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via Retry.remove_headers_on_redirect.

Full Changelog: https://github.com/urllib3/urllib3/compare/1.26.18...1.26.19

Note that due to an issue with our release automation, no multiple.intoto.jsonl file is available for this release.

• Made body stripped from HTTP requests changing the request method to GET after HTTP 303 "See Other" redirect responses. (GHSA-g4mx-q9vg-27p4)

• Added the Cookie header to the list of headers to strip from requests when redirecting to a different host. As before, different headers can be set via Retry.remove_headers_on_redirect. (GHSA-v845-jxx5-vc9f)

• Fixed thread-safety issue where accessing a PoolManager with many distinct origins would cause connection pools to be closed while requests are in progress (#2954)

• Fix socket timeout value when HTTPConnection is reused (https://github.com/urllib3/urllib3/issues/2645)
• Remove "!" character from the unreserved characters in IPv6 Zone ID parsing (https://github.com/urllib3/urllib3/issues/2899)
• Fix IDNA handling of 'x80' byte (https://github.com/urllib3/urllib3/issues/2901)

• Fixed parsing of port 0 (zero) returning None, instead of 0 (#2850)
• Removed deprecated HTTPResponse.getheaders() calls in urllib3.contrib module.

• Deprecated the HTTPResponse.getheaders() and HTTPResponse.getheader() methods.
• Fixed an issue where parsing a URL with leading zeroes in the port would be rejected even when the port number after removing the zeroes was valid.
• Fixed a deprecation warning when using cryptography v39.0.0.
• Removed the <4 in the Requires-Python packaging metadata field.

• Deprecated the urllib3[secure] extra and the urllib3.contrib.pyopenssl module. Both will be removed in v2.x. See this GitHub issue for justification and info on how to migrate.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors.

:warning: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Fixed an issue where reading more than 2 GiB in a call to HTTPResponse.read would raise an OverflowError on Python 3.9 and earlier.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors.

:warning: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

:closed_lock_with_key: This is the first release to be signed with Sigstore! You can verify the distributables using the .sig and .crt files included on this release.

• Removed support for Python 3.5
• Fixed an issue where a ProxyError recommending configuring the proxy as HTTP instead of HTTPS could appear even when an HTTPS proxy wasn't configured.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors.

:warning: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

:warning: This release will be the last release supporting Python 3.5. Please upgrade to a non-EOL Python version.

• Changed urllib3[brotli] extra to favor installing Brotli libraries that are still receiving updates like brotli and brotlicffi instead of brotlipy. This change does not impact behavior of urllib3, only which dependencies are installed.
• Fixed a socket leaking when HTTPSConnection.connect() raises an exception.
• Fixed server_hostname being forwarded from PoolManager to HTTPConnectionPool when requesting an HTTP URL. Should only be forwarded when requesting an HTTPS URL.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors.

:warning: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

:warning: This release will be the last release supporting Python 3.5. Please upgrade to a non-EOL Python version.

• Added extra message tourllib3.exceptions.ProxyError when urllib3 detects that a proxy is configured to use HTTPS but the proxy itself appears to only use HTTP.
• Added a mention of the size of the connection pool when discarding a connection due to the pool being full.
• Added explicit support for Python 3.11.
• Deprecated the Retry.MAX_BACKOFF class property in favor of Retry.DEFAULT_MAX_BACKOFF to better match the rest of the default parameter names. Retry.MAX_BACKOFF is removed in v2.0.
• Changed location of the vendored ssl.match_hostname function from urllib3.packages.ssl_match_hostname to urllib3.util.ssl_match_hostname to ensure Python 3.10+ compatibility after being repackaged by downstream distributors.
• Fixed absolute imports, all imports are now relative.

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Fixed a bug with HTTPS hostname verification involving IP addresses and lack of SNI
• Fixed a bug where IPv6 braces weren't stripped during certificate hostname matching

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Deprecated the urllib3.contrib.ntlmpool module. urllib3 is not able to support it properly due to reasons listed in this issue. If you are a user of this module please leave a comment.
• Changed HTTPConnection.request_chunked() to not erroneously emit multiple Transfer-Encoding headers in the case that one is already specified.
• Fixed typo in deprecation message to recommend Retry.DEFAULT_ALLOWED_METHODS.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Fixed deprecation warnings emitted in Python 3.10.
• Updated vendored six library to 1.16.0.
• Improved performance of URL parser when splitting the authority component.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Changed behavior of the default SSLContext when connecting to HTTPS proxy during HTTPS requests. The default SSLContext now sets check_hostname=True.

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Fixed bytes and string comparison issue with headers (Pull #2141)

• Changed ProxySchemeUnknown error message to be more actionable if the user supplies a proxy URL without a scheme (Pull #2107)

If you or your organization rely on urllib3 consider supporting us via GitHub Sponsors

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Fixed an issue where wrap_socket and CERT_REQUIRED wouldn't be imported properly on Python 2.7.8 and earlier (Pull #2052)

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Fixed an issue where two User-Agent headers would be sent if a User-Agent header key is passed as bytes (Pull #2047)

:warning: IMPORTANT: urllib3 v2.0 will drop support for Python 2: Read more in the v2.0 Roadmap

• Added support for HTTPS proxies contacting HTTPS servers (Pull #1923, Pull #1806)

• Deprecated negotiating TLSv1 and TLSv1.1 by default. Users that still wish to use TLS earlier than 1.2 without a deprecation warning should opt-in explicitly by setting ssl_version=ssl.PROTOCOL_TLSv1_1 (Pull #2002) Starting in urllib3 v2.0: Connections that receive a DeprecationWarning will fail

• Deprecated Retry options Retry.DEFAULT_METHOD_WHITELIST, Retry.DEFAULT_REDIRECT_HEADERS_BLACKLIST and Retry(method_whitelist=...) in favor of Retry.DEFAULT_ALLOWED_METHODS, Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT, and Retry(allowed_methods=...) (Pull #2000) Starting in urllib3 v2.0: Deprecated options will be removed

• Added default User-Agent header to every request (Pull #1750)

• Added urllib3.util.SKIP_HEADER for skipping User-Agent, Accept-Encoding, and Host headers from being automatically emitted with requests (Pull #2018)

• Collapse transfer-encoding: chunked request data and framing into the same socket.send() call (Pull #1906)

• Send http/1.1 ALPN identifier with every TLS handshake by default (Pull #1894)

• Properly terminate SecureTransport connections when CA verification fails (Pull #1977)

• Don't emit an SNIMissingWarning when passing server_hostname=None to SecureTransport (Pull #1903)

• Disabled requesting TLSv1.2 session tickets as they weren't being used by urllib3 (Pull #1970)

• Suppress BrokenPipeError when writing request body after the server has closed the socket (Pull #1524)

• Wrap ssl.SSLError that can be raised from reading a socket (e.g. "bad MAC") into an urllib3.exceptions.SSLError (Pull #1939)

• Fix retry backoff time parsed from Retry-After header when given in the HTTP date format. The HTTP date was parsed as the local timezone rather than accounting for the timezone in the HTTP date (typically UTC) (#1932, #1935, #1938, #1949)

• Fix issue where an error would be raised when the SSLKEYLOGFILE environment variable was set to the empty string. Now SSLContext.keylog_file is not set in this situation (#2016)

• Added support for SSLKEYLOGFILE environment variable for logging TLS session keys with use with programs like Wireshark for decrypting captured web traffic (Pull #1867)

• Fixed loading of SecureTransport libraries on macOS Big Sur due to the new dynamic linker cache (Pull #1905)

• Collapse chunked request bodies data and framing into one call to send() to reduce the number of TCP packets by 2-4x (Pull #1906)

• Don't insert None into ConnectionPool if the pool was empty when requesting a connection (Pull #1866)

• Avoid hasattr call in BrotliDecoder.decompress() (Pull #1858)

• Added InvalidProxyConfigurationWarning which is raised when erroneously specifying an HTTPS proxy URL. urllib3 doesn't currently support connecting to HTTPS proxies but will soon be able to and we would like users to migrate properly without much breakage.

  See this GitHub issue for more information on how to fix your proxy config. (Pull #1851)

• Drain connection after PoolManager redirect (Pull #1817)

• Ensure load_verify_locations raises SSLError for all backends (Pull #1812)

• Rename VerifiedHTTPSConnection to HTTPSConnection (Pull #1805)

• Allow the CA certificate data to be passed as a string (Pull #1804)

• Raise ValueError if method contains control characters (Pull #1800)

• Add __repr__ to Timeout (Pull #1795)

• Drop support for EOL Python 3.4 (Pull #1774)

• Optimize _encode_invalid_chars (Pull #1787)

• Preserve chunked parameter on retries (Pull #1715, Pull #1734)

• Allow unset SERVER_SOFTWARE in App Engine (Pull #1704, Issue #1470)

• Fix issue where URL fragment was sent within the request target. (Pull #1732)

• Fix issue where an empty query section in a URL would fail to parse. (Pull #1732)

• Remove TLS 1.3 support in SecureTransport due to Apple removing support (Pull #1703)

• Fix issue where tilde (~) characters were incorrectly percent-encoded in the path. (Pull #1692)

• Add mitigation for BPO-37428 affecting Python <3.7.4 and OpenSSL 1.1.1+ which caused certificate verification to be enabled when using cert_reqs=CERT_NONE. (Issue #1682)

• Propagate Retry-After header settings to subsequent retries. (Pull #1607)

• Fix edge case where Retry-After header was still respected even when explicitly opted out of. (Pull #1607)

• Remove dependency on rfc3986 for URL parsing.

• Fix issue where URLs containing invalid characters within Url.auth would raise an exception instead of percent-encoding those characters.

• Add support for HTTPResponse.auto_close = False which makes HTTP responses work well with BufferedReaders and other io module features. (Pull #1652)

• Percent-encode invalid characters in URL for HTTPConnectionPool.request() (Pull #1673)

• Change HTTPSConnection to load system CA certificates when ca_certs, ca_cert_dir, and ssl_context are unspecified. (Pull #1608, Issue #1603)

• Upgrade bundled rfc3986 to v1.3.2. (Pull #1609, Issue #1605)

• Change is_ipaddress to not detect IPvFuture addresses. (Pull #1583)

• Change parse_url to percent-encode invalid characters within the path, query, and target components. (Pull #1586)

• Add support for Google's Brotli package. (Pull #1572, Pull #1579)
• Upgrade bundled rfc3986 to v1.3.1 (Pull #1578)

• Require and validate certificates by default when using HTTPS (Pull #1507)

• Upgraded urllib3.utils.parse_url() to be RFC 3986 compliant. (Pull #1487)

• Added support for key_password for HTTPSConnectionPool to use encrypted key_file without creating your own SSLContext object. (Pull #1489)

• Add TLSv1.3 support to CPython, pyOpenSSL, and SecureTransport SSLContext implementations. (Pull #1496)

• Switched the default multipart header encoder from RFC 2231 to HTML 5 working draft. (Issue #303, Pull #1492)

• Fixed issue where OpenSSL would block if an encrypted client private key was given and no password was given. Instead an SSLError is raised. (Pull #1489)

• Added support for Brotli content encoding. It is enabled automatically if brotlipy package is installed which can be requested with urllib3[brotli] extra. (Pull #1532)

• Drop ciphers using DSS key exchange from default TLS cipher suites. Improve default ciphers when using SecureTransport. (Pull #1496)

• Implemented a more efficient HTTPResponse.__iter__() method. (Issue #1483)

• Apply fix for CVE-2019-9740. (Pull #1591)