What's Changed

• docs: release notes 1.4.8 by @johanandren in #847
• fix: origin line numbers after newline separators by @mattheworford in #850
• feat: opt-in unknown key validation for ConfigBeanFactory by @mattheworford in #851
• fix: wrong line number for objects after multiline string by @mattheworford in #853

New Contributors

• @mattheworford made their first contribution in #850

Full Changelog: v1.4.8...v1.4.9

• fix: origin line numbers after newline separators (#850) thanks to @mattheworford
• feat: opt-in unknown key validation for ConfigBeanFactory (#851) thanks to @mattheworford
• fix: wrong line number for objects after multiline string (#853) thanks to @mattheworford

What's Changed

• fix: BugOrBroken - partially-shadowed object has nested delayed merge by @johanandren in #846

Full Changelog: v1.4.7...v1.4.8

• fix: BugOrBroken - partially-shadowed object has nested delayed merge, fix for regression introduced in 1.4.7, (#846) thanks to @johanandren

What's Changed

• docs: adjust description of release process by @sebastian-alfers in #834
• docs: Update NEWS with latest two releases by @johanandren in #835
• CI fixes by @jsoref in #843
• Fix spelling by @jsoref in #840
• fix: rendering of substituted list with space by @johanandren in #841
• fix: Don't evaluate substitutions hidden by values from resolved objects by @johanandren in #839
• Drop the broken Maven chip in Readme by @ennru in #844

New Contributors

• @jsoref made their first contribution in #843

Full Changelog: v1.4.6...v1.4.7

• fix: rendering of substituted list with space (#841) thanks to @johanandren
• fix: Don't evaluate substitutions hidden by values from resolved objects (#839) thanks to @johanandren
• build: CI improvements (#843) thanks to @jsoref
• docs: spelling improvements by (#840) thanks to @jsoref

What's Changed

• Render list elements as non-root always by @valepakh in #832
• List expansion from environment variables by @johanandren in #833

New Contributors

• @valepakh made their first contribution in #832

Full Changelog: v1.4.5...v1.4.6

• Support for list substitution from environment variables (#833) thanks to @johanandren
• Render list elements as non-root always by (#832) thanks to @valepakh

What's Changed

• docs: add alternative Rust HOCON implementation by @mikai233 in #825
• Fix minor typos in API docs by @lashchenko in #823
• update HOCON Playground link by @TehBrian in #810
• fix: Negative hash again by @johanandren in #826

New Contributors

• @mikai233 made their first contribution in #825
• @lashchenko made their first contribution in #823
• @TehBrian made their first contribution in #810

Full Changelog: v1.4.4...v1.4.5

• docs: add alternative Rust HOCON implementation (#825) thanks to @mikai233
• Fix minor typos in API docs (#823) thanks to @lashchenko
• update HOCON Playground link (#810) thanks to @TehBrian
• fix: Negative hash again (#826) thanks to @johanandren

1.4.4: July 10, 2025

• build: bump actions to get sbt (#818) thanks to @johanandren
• build: second try for sbt back in CI job (#820) thanks to @johanandren
• fix: Incorrect abs of hashes in BadMap (#817) thanks to @johanandren

• build: bump actions to get sbt (#818) thanks to @johanandren
• build: second try for sbt back in CI job (#820) thanks to @johanandren
• fix: Incorrect abs of hashes in BadMap (#817) thanks to @johanandren

What's Changed

• Release 1.4.2 by @raboof in #759
• add note with clarification how to pass -Dconfig properly; taken from… by @iamtodor in #763
• readme: change playground url by @av-elier in #775
• Update maintenance note by @ennru in #788
• Make the issue template work by @ennru in #791
• fix: Optionally hide rendered environment variables by @patriknw in #798
• chore: update NEWS and release 1.4.3 by @patriknw in #799

New Contributors

• @iamtodor made their first contribution in #763
• @patriknw made their first contribution in #798

Full Changelog: v1.4.2...v1.4.3

• Optionally hide rendered environment variables (#798)

• Avoid instantiating arbitrary classes (#758) thanks to @vlsi for the report and @raboof for the patch
• Various project infrastructure improvements (#755, #757) thanks to @ennru
• Add hoplite to Kotlin wrappers (#749) thanks to @sksamuel
• Remove unnecessary array (#730) thanks to @hkupty
• Add erlang port to README (#722) thanks to @6293
• Update repo path for Ficus (#694) thanks to @joyfulvillage
• Fix wrong URL in NEWS.md (#723) thanks to @lukaszlenart

• introduce docs for arrays on env vars (#706), (#710) and (#711) thanks to @ignasi35 and @andreaTP
• add a helper method for parsing only application overrides (#708) and (#709) thanks to @bbaldino
• remove unmodifiable collection wrappers in ResolveContext (#701) thanks to @havocp
• added support for memory units which don't fit in a long when transformed to bytes (#663) thanks to @mpryahin
• inherit optional and getter evaluation (#660) thanks to @derKrischan
• a few other bug fixes

• application.conf variables can now override variables in reference.conf #619
• performance improvement through capacity hint for ArrayList #648

(This was previously published as 1.3.5-RC1 but deemed a large enough change to require a minor version rather than a patch)

• it is now possible to override any configuration setting from environment variables (#620) thanks to @andreaTP
• added support for integer keys that are longer than Int (#568) thanks to @michalmela
• Missing exception now has a reference to the origin Config (#585) thanks to @vagola
• performance improvements to resolve() (#578) thanks to @sam-token
• config file syntax is now resolved when parsing InputStream (#573) thanks to @ntviet18
• it is now possible to use @Optional on keys that are reserved words (#570) thanks to @radist-nt
• ValidationProblem is now serializable (#437) thanks to @iantabolt

All of the merged PRs can be found in the release milestone.

• artifact now includes Automatic-Module-Name which makes it consumable as Java 9 module.
• minor issue fix. All of the fixed issues can be found in the milestone page.

• environment variables are now able to be resolved to lists in the same fashion as system properties.
• added getPeriod() which returns time units as java.time.Period. Currently supported periods are days, weeks, months and years. More information here.
• ConfigResolveOptions now has appendResolver(...) which allows having custom behavior when unresolved substitutions are encountered during resolution.
• Config Beans now support Set collection.
• a few other small bugfixes. All of the fixed issues can be found in the milestone page.

• added include required("foo") syntax to specify includes that fail if not present
• support for more kinds of property in ConfigBeanFactory:
  • enumerations
  • optional fields
  • lists of beans
• numbers can now start with a decimal (".33" vs. "0.33"), these are still parsed as strings but Config.getDouble() etc. will convert them to numbers
• a few other small bugfixes

• no changes from 1.3.0-M3
• this is an ABI-guaranteed stable release.
• 1.3.0 should be ABI-compatible with 1.2.x for most applications, though there are enough changes to corner cases and implementation that some obscure things could break. Please see the notes for the 1.3.0 milestones below for details, especially for 1.3.0-M1.

• this is an ABI-not-guaranteed beta release in advance of 1.3.0. Please see the notes for 1.3.0-M1 below for warnings, caveats, and the bulk of what's changed since 1.2.1.

API changes (since 1.3.0-M2):

• renamed some methods in the new ConfigDocument for consistency with Config (breaks ABI vs. 1.3.0-M2, but not vs. any stable release)

Fixes:

• couple of bugfixes in ConfigDocument

Thank you to contributors with commits since v1.3.0-M2 tag:

• Preben Ingvaldsen

• not in fact an April Fool's joke. Unless it's broken. Then it was.
• this is an ABI-not-guaranteed beta release in advance of 1.3.0. Please see the notes for 1.3.0-M1 below for warnings, caveats, and the bulk of what's changed since 1.2.1.
• this release churns the internals a good bit since 1.3.0-M1, so would benefit from your testing efforts.

New API (since 1.3.0-M1):

• added Config.hasPathOrNull
• added Config.getIsNull
• added parser.ConfigDocument which supports simple load/edit/save on a config file. For now, the only allowed edits are removing/replacing values. This was a major effort (redoing the whole parser), implemented by Preben Ingvaldsen.

Fixes:

• added missing @since tags to javadoc
• fixed obscure bug in converting to camel case when instantiating beans

Thank you to contributors with commits since v1.3.0-M1 tag:

• Glen Ford
• Jay McCure
• Preben Ingvaldsen

• this is an ABI-not-guaranteed beta release in advance of 1.3.0. The public, documented ABI should not be broken vs. 1.2.0; however, there are enough changes that something certainly could break, and some obscure corner cases have changed semantics and that could bite some people.

Changes that are most likely to break something:

• now built with Java 8 and requires Java 8
• if you were relying on the order of key iteration in a config, note that Java 8 changed the iteration order for hashes and that includes Config and ConfigObject
• several correctness fixes to resolving substitutions (the ${foo} syntax). These should only matter in weird corner cases, but some people did encounter the problems such as in #177.
• throw an exception if a size-in-bytes values are out of Long range #170
• two adjacent undefined concatenation elements (like ${?foo}${?bar}) now become undefined instead of throwing an exception
• when rendering a path that starts with a digit, don't put quotes around it
• set the Accept header on http requests when loading config from a URL
• when getting a 404 from a URL, treat it as a missing file (silently ignore) instead of throwing exception. Other error codes will still throw an exception.
• ConfigParseOptions.prependIncluder/appendIncluder always throw when given a null includer, formerly they only threw sometimes

New API:

• ConfigBeanFactory will auto-fill a JavaBean from a Config
• it is now possible to create a ConfigOrigin using ConfigOriginFactory and to modify origins on values using ConfigValue.withOrigin
• Config.getMemorySize returns a ConfigMemorySize
• Config.getDuration returns a java.time.Duration
• the existing ConfigValueFactory.fromAnyRef and related methods now pass through a ConfigValue instead of throwing an exception
• ConfigFactory.defaultApplication() returns the default Config used by ConfigFactory.load() in between defaultReference() and defaultOverrides(), leaving ConfigFactory.load() as a trivial convenience API that uses no internal magic.

Improvements:

• allow duration abbreviations "nanos", "millis", "micros"
• Config.hasPath is now much faster, so if you were caching to avoid this you may be able to stop
• new debug option -Dconfig.trace=substitutions explains how ${foo} references are being resolved
• sort numeric keys in numeric order when rendering
• allow whitespace in between two substitutions referring to objects or lists when concatenating them, so ${foo} ${bar} and ${foo}${bar} are now the same if foo and bar are objects or lists.
• better error messages for problems loading resources from classpath, now we show the jar URL that failed
• even more test coverage!
• lots of minor javadoc fixes
• method names in javadoc now link to github source

Bug fixes:

• fix "allow unresolved" behavior for unresolved list elements
• class loaders are cached with a WeakReference to avoid leaks #171
• create valid output for values with multiline descriptions #239
• -Dsun.io.serialization.extendedDebugInfo=true no longer explodes due to calling toString on an internal object, #176

Thank you to contributors with commits since v1.2.1 tag:

• Alex Wei
• Andrey Zaytsev
• Ben Jackman
• Ben McCann
• Chris Martin
• Dale Wijnand
• Francois Dang Ngoc
• ian
• KAWACHI Takashi
• Kornel Kielczewski
• Lunfu Zhong
• Michel Daviot
• Paul Phillips
• Pavel Yakunin
• Preben Ingvaldsen
• verbeto
• Wu Zhenwei

• bugfix release, no API additions or changes
• fix resolving substitutions in include statements nested inside objects
• when rendering an object to a string, sort the fields
• handle unresolved substitutions in value concatenations
• make ConfigOrigin.comments unmodifiable
• when using '+=' or 'include' inside a list, throw an exception instead of generating a wrong result
• when context class loader is unset throw a more helpful exception than NullPointerException
• ignore non-string values in a Properties object

• new stable ABI release (binary compatible with 1.0.x; a few new APIs)
• new API ConfigResolveOptions.setAllowUnresolved lets you partially-resolve a Config
• new API Config.isResolved lets you check on resolution status
• new API Config.resolveWith lets you source substitutions from somewhere other than the Config itself
• new API Config.getDuration() replaces getMilliseconds and getNanoseconds
• if -Dconfig.file, -Dconfig.resource, -Dconfig.url refer to a nonexistent file, resource, or url it is now an error rather than silently loading an empty configuration.
• quite a few bugfixes

• this is a snapshot/preview with API/ABI additions. New API since 1.0.x is NOT guaranteed to remain compatible for now since the purpose of this release is to test it. This release is supposed to be ABI-compatible with 1.0.x however.
• snapshots now use the git hash they are based on in the version, instead of SNAPSHOT, so they are a stable reference if you want to test them out.
• if -Dconfig.file, -Dconfig.resource, -Dconfig.url refer to a nonexistent file, resource, or url it is now an error rather than silently loading an empty configuration.
• new API Config.getDuration() replaces getMilliseconds and getNanoseconds. (should it return long instead of Long even though it's been in git for a while? weigh in at https://github.com/lightbend/config/issues/119 )
• new API ConfigResolveOptions.setAllowUnresolved lets you partially-resolve a Config
• new API Config.isResolved lets you check on resolution status
• new API Config.resolveWith lets you source substitutions from somewhere other than the Config itself
• compiled with debug symbols
• add -Dconfig.trace=loads feature to trace loaded files and failures
• improvements to ConfigObject render() formatting so you can print out a config in a prettier way
• attempt to honor Content-Type when loading from a URL
• a fair list of corner case bugfixes

• remove junk in POM caused by broken local configuration
• build jar using Java 1.6 (and enforce this in build)
• change getDuration to return unboxed long instead of boxed
• API documentation improvements https://lightbend.github.io/config/latest/api/

• ignore byte-order mark (BOM), treating it as whitespace
• very minor docs/build improvements

• when an array is requested and an object found, try to convert the object to an array if the object has numeric keys in it. This is intended to support -Dfoo.0=bar, -Dfoo.1=baz which would create foo : { "0" : "bar", "1" : "baz" }; which in turn could now be treated as if it were foo : ["bar","baz"]. This is useful for creating array values on the command line using Java system properties.
• fix a ConcurrentModificationException if an app modified system properties while we were trying to parse them.
• fix line numbering in error messages for newlines within triple quotes.

• no changes from 0.6.0. ABI now guaranteed for 1.0.x series.

• add ConfigRenderOptions.setJson which can be used to enable or disable the use of HOCON extensions (other than comments, which remain separately-controlled). Right now setJson(false) will result in a somewhat prettier rendering using extensions.
• add ConfigFactory.invalidateCaches() to support reloading system properties (mostly this is intended for use in unit tests).
• make ConfigException serializable, in case you have some logging system or similar that relies on that. Serialization of ConfigException is not guaranteed to be compatible across releases.

• add versions of ConfigFactory.load() which let you specify ConfigParseOptions and ConfigResolveOptions.

• triple-quoted strings as in Python or Scala
• obscure backward incompatibilities:
  • """" previously parsed as two empty strings concatenated into a single empty string, now it parses as an unterminated triple-quoted string.
  • a triple-quoted string like """\n""" previously parsed as an empty string, a string with one newline character, and another empty string, all concatenated into a single string. Now it parses as a string with two characters (backslash and lowercase "n").
  • in short you could have two adjacent quoted strings before, where one was an empty string, and now you can't. As far as I know, the empty string was always worthless in this case and can just be removed.
• added methods atPath() and atKey() to ConfigValue, to wrap the value into a Config
• added method withValue() to Config and ConfigObject, to add a value at a given path or key

• publish as OSGi bundle

• this is rolling toward 1.0 and should be pretty much feature-complete.
• this version is published on Maven central so you need to update your dependency coordinates
• the serialization format has changed to one that's extensible and lets the library evolve without breaking serialization all the time. The new format is also much more compact. However, this change is incompatible with old serializations, if you rely on that. The hope is to avoid serialization breakage in the future now that the format is not the default Java one (which was a direct dump of all the implementation details).
• serializing an unresolved Config (one that hasn't had resolve() called on it) is no longer supported, you will get NotSerializableException if you try.
• ConfigValue.render() now supports ConfigRenderOptions which means you can get a no-whitespace no-comments plain JSON rendering of a ConfigValue
• supports self-referential substitutions, such as path=${path}":/bin", by "looking backward" to the previous value of path
• supports concatenating arrays and merging objects within a single value. So you can do path=${path} [ "/bin" ] for example. See README and spec for more details.
• supports array append += where path+="/bin" expands to path=${?path} [ "/bin" ]
• supports specifying type of include include url("http://example.com/"), include file("/my/file.conf"), and include classpath("whatever"). This syntax forces treatment as URL, file, or classpath resource.
• supports including URLs include "http://example.com/whatever.conf" (if an include is a valid URL, it's loaded as such). This is incompatible with prior versions, if you have a filename that is also a valid URL, it would have loaded previously but now it will not. Use the include file("") syntax to force treatment as a file.
• class loaders are now recursively inherited through include statements; previously, even if you set a custom class loader when parsing a file, it would not be used for parsing a classpath resource included from the file.
• parseString() and parseReader() now support include statements in the parsed string or reader
• in -Dconfig.resource=name, name can start with a "/" or not, doesn't matter
• if you implement ConfigIncluder, you should most likely also implement ConfigIncluderFile, ConfigIncluderURL, and ConfigIncluderClasspath. You should also use ConfigIncludeContext.parseOptions() if appropriate.
• cycles in include statements (self-includes) are now detected and result in a nicer error instead of stack overflow
• since 0.3.0, there is an obscure incompatible semantic change in that self-referential substitutions where the cycle could be broken by partially resolving the object now "look backward" and may fail to resolve. This is not incompatible with the version included in Play/Akka 2.0 because in that version this obscure case just threw an exception. But in 0.3.0 there were cases that worked that now work differently. You are very unlikely to be affected by this.
• Play/Akka 2.0 do not and will not have the new stuff in this version due to the serialization break, they will update next time they bump their ABI.

• 0.3.1 is a backport of the "-Dconfig.resource=name can start with a /" fix to 0.3.0
• 0.3.1 was published on Maven Central while 0.3.0 and earlier are only on Typesafe's repository
• 0.3.1 is mostly intended for use by Akka 2.0.x (and therefore Play 2.0.x), everyone else should use a higher version number