RELEASE-NOTES-1.39

= MediaWiki 1.39 =

== MediaWiki 1.39.0-rc.1 ==

=== Changes since MediaWiki 1.39.0-rc.0 ===
* Localisation updates.
* (T318754) WebInstallerOptions::addPersonalizationOptions(): Close fieldset
* (T306802) docker: update to latest published images
* (T318307) HTMLFormField::validate(): Update docs to permit all data types
* (T318460) SpecialChangeEmail: Set default for returntoquery
* (T318481) composer: Drop symfony/php73-polyfill
* …

== MediaWiki 1.39.0-rc.0 ==

THIS IS NOT A RELEASE YET

MediaWiki 1.39 is a pre-release testing branch, and is not recommended
for use in production.

== Upgrading notes for 1.39 ==
Don't forget to always back up your database before upgrading!

See the file UPGRADE for more detailed per-version upgrade instructions from the
oldest supported upgrading version, MediaWiki 1.31.

Some specific notes for MediaWiki 1.39 upgrades are below:
* (T278139) Drop PHP 7.3 support in MediaWiki 1.39; require 7.4.3 or higher.

For notes on 1.38.x and older releases, see HISTORY.

=== Configuration changes for system administrators in 1.39 ===

==== New configuration ====
* $wgAutoCreateTempUser – This configures automatic user creation on page save.
* $wgCopyUploadAllowOnWikiDomainConfig – This configures if administrators can
  use the MediaWiki:Copyupload-allowed-domains system message to define which
  domains can be used with the upload-by-url tool.
* $wgCdnMatchParameterOrder – This can be set to false if MediaWiki is behind a
  CDN that re-orders query parameters. This will make the code that matches
  request URLs to canonical CDN URLs insensitive to parameter order.
* $wgMultiShardSiteStats – This allows you to split site_stats across multiple
  rows. Only useful for very large, heavily edited wikis. (T306589)

==== Changed configuration ====
* $wgInvalidUsernameCharacters – This setting now contains the char '>', which
  is now the reserved delimiter for external user names.
* $wgLocalFileRepo – The default serialization method for file meta-data has
  been changed to JSON. You can revert it to PHP by setting the property
  'useJsonMetadata' to false.
* $wgLBFactoryConf – The 'configCallback' flag can now be set to a callback
  function that returns an array with keys to update in $wgLBFactoryConf. This
  can be used to update the database configuration on the fly, e.g. to take
  replica hosts out of rotation.
* $wgDBservers and $wgLBFactoryConf – The DBO_SSL flag in has been deprecated in
  favour of a boolean "ssl" parameter.
* $wgObjectCaches – The 'globalKeyLB' and 'localKeyLB' flags are no longer
  supported.

==== Removed configuration ====
* $wgMultiContentRevisionSchemaMigrationStage - This transition flag, deprecated
  since MediaWiki 1.35, has been removed; the data migration is over.
* $wgActorTableSchemaMigrationStage - This transition flag has been removed; the
  data migration is over.
* $wgWikiFarmSiteDetector – This experimental setting has been removed without
  replacement. Use the MW_WIKI_NAME environment variable to specifiy the name of
  the site for which to load configuration. Using the WIKI_NAME environment
  variable for this purpose is deprecated.
* $wgParserCacheUseJson - The ParserCache now always uses JSON serialization.
  Reading old non-JSON cache entries is still supported. The setting had been
  deprecated since 1.36.
* $wgAllowJavaUploads - To allow uploads of JAR files, remove application/java
  from $wgMimeTypeExclusions.
* $wgMaxRedirects – This broken feature was removed, as it never worked as
  intended (T296430).
* $wgElementTiming – This experimental, default-disabled feature has been
  removed without replacement.
* $wgPriorityHints and $wgPriorityHintsRatio – The related experimental feature
  has been removed without replacement.
* $wgIncludeLegacyJavaScript – This flag has been removed, without loss of any
  functionality in this release. Most former "wikibits" functions were removed
  after deprecation in previous releases. The remaining functions, such as
  importScript, are now available unconditionally.
* $wgLegacySchemaConversion - This unused setting has been removed.
* $wgInterwikiPrefixDisplayTypes - This unused setting has been removed.
* $wgMangleFlashPolicy – This is no longer functional, and is now deprecated.
  Users who are somehow still using Flash as a browser extension will be exposed
  to CSRF vulnerabilities.

=== New user-facing features in 1.39 ===
* Optional automatic user creation on page save ($wgAutoCreateTempUser)
* Administrators now have the option to delete/undelete the associated "Talk"
  page when they are (un)deleting a given page. `deletetalk` and `undeletetalk`
  options were added to the 'delete' and 'undelete' action APIs in MW 1.38.
* `{{=}}` is now a wikitext built-in magic word, expanding to `=`.  This is
  conventionally used as an escape mechanism to allow the use of `=` in
  unnamed template arguments.  Defining [[Template:=]] to expand to something
  other than `=` has been deprecated since 1.36, with affected pages put into
  a special tracking category for migration.
* (T284020) Bot passwords are now supported when using the REST API.

=== New developer features in 1.39 ===
* Added optional $size param to SearchResultProvideThumbnail hook.
* SearchResultProvideThumbnail hook interface moved from MediaWiki\Rest\Hook
  namespace to MediaWiki\Search\Hook.
* JsonValidateSaveHook has been added to allow extensions to set additional
  pre-save validations for specific JSON pages (T313254)
* Added 'PermissionErrorAudit' hook, enabling extensions to audit permission
  errors on specfic actions. For instance account registration failed attempts
  due to a block (T306018).

=== External library changes in 1.39 ===

==== New external libraries ====
* Added Codex v0.1.1. This replaces the now deprecated wvui library.

===== New development-only external libraries =====
* Updated QUnit from 2.18.0 to 2.18.2.

==== Changed external libraries ====
* Updated jQuery from v3.6.0 to v3.6.1.
* Updated OOUI from v0.43.2 to v0.44.3.
* Updated composer/semver from 3.2.6 to 3.3.2.
* Updated symfony/polyfill-php73 from 1.25.0 to 1.26.0.
* Updated symfony/polyfill-php80 from 1.25.0 to 1.26.0.
* Updated symfony/yaml from 5.4.3 to 5.4.10.
* Updated vue/compat from 3.2.23 to 3.2.37.
* Updated wikimedia/base-convert from 2.0.1 to 2.0.2.
* Updated wikimedia/ip-set from 3.0.0 to 3.1.0.
* Updated wikimedia/minify from 2.2.6 to 2.3.0.
* Updated wikimedia/php-session-serializer from 2.0.0 to 2.0.1.
* Updated wikimedia/running-stat from 1.2.1 to 2.1.0.
* Updated wikimedia/scoped-callback from 3.0.0 to 4.0.0.
* Updated wikimedia/services from 2.0.1 to 3.0.0.
* Updated wikimedia/timestamp from 3.0.0 to 4.0.0.
* Updated wikimedia/xmp-reader from 0.8.1 to 0.8.3.

===== Changed development-only external libraries =====
* Updated composer/spdx-licenses from 1.5.5 to 1.5.6.
* Updated doctrine/dbal for PHP < 7.3 from 2.13.6 to 2.13.9.
* Updated doctrine/dbal for PHP >= 7.3 from 3.1.5 to 3.4.2.

=== Bug fixes in 1.39 ===
* (T314013) $wgExtraNamespaces no longer overrides canonical namespace names
  specified in extension.json files. While this setting can still be used to
  rename extension-defined namespaces, system administrators may need to run
  namespaceDupes.php after upgrading.

=== Action API changes in 1.39 ===
* New `undeletetalk` parameter on action=undelete that allows you to restore
  all revisions of the associated talk page.

=== Languages updated in 1.39 ===
MediaWiki supports over 350 languages. Many localisations are updated regularly.
Below only new and removed languages are listed, as well as changes to languages
because of Phabricator reports.

* Actual localization was added for several languages, which were already
  in Names.php and even used for a Wikipedia:
** (T313200) Added language support for Rundi (Kirundi, rn).
** (T310976) Added language support for Tumbuka (ChiTumbuka, tum).
** (T314270) Added language support for Kanuri (kr).
* (T313199) Added language support for Sylheti (syl).
* (T311975) Added language support for Ghanaian Pidgin (gpe).
* (T307080) Added language support for Okinawan (ryu).
* (T307887) Added language support for Mooré (mos).
* (T308813) Added language support for Nigerian Pidgin (pcm).
* (T309763) Added language support for Tai Nüa (tdd).
* (T310040) Added language support for Fante (fat).
* (T311034) Added language support for Campidanese Sardinian (sro).
* (T315406) Fix the autonym of the Iñupiaq language to "Iñupiatun".
* (T315677) Removed French fallback from the Fula language (ff).
* (T304920) In Swahili, The "Media" namespace is now "Media", as in English,
  and the "File" namespace is now "Faili". The old name of the "File" namespace
  was "Picha", and it's kept for backwards compatibility. If you manage a wiki
  in Swahili, and you use "Faili:" as a namespace anywhere in wikitext, and
  you mean to use it as "Media:", these need to be replaced to "Media:".
* (T309866) Some namespace translations were updated for Kyrgyz (ky). The old
  ones are retained as aliases for backwards compatibility.
* (T117845) Started the renaming of the language codes for Serbian from sr-ec
  and sr-el to sr-cyrl and sr-latn.

=== Breaking changes in 1.39 ===
* Basic non-JavaScript (Grade C) support has been dropped for Internet Explorer
  9-10, Firefox 27-38, and Android 4.3-4.4.
* The following methods, deprecated since 1.37, have been removed from IDatabase
  - ::fetchObject()
  - ::fetchRow()
  - ::numRows()
  - ::freeResult()
* Title::getDefaultNamespace(), deprecated since 1.37, has been removed.
* The DBPrimaryPos class alias 'DBMasterPos' has been removed.
* The global function wfGetLB(), deprecated since 1.27, has been removed.
* Passing a db to BlockRestrictionStore::loadByBlockId() is no longer supported.
  BlockRestrictionStoreFactory should be used to fetch a correct
  BlockRestrictionStore instead. This was deprecated since 1.38.
* The global function wfGetCache(), deprecated since 1.32, has been removed. You
  can use ObjectCache::getInstance() instead.
* The global function wfGetMainCache(), deprecated since 1.32, has been removed.
  You can use ObjectCache::getLocalClusterInstance() instead.
* MovePage::__construct() now requires that all parameters be passed. The
  fallback to MediaWikiServices emitted deprecation notices since 1.37.
* WikiPage::doEditContent(), deprecated since 1.32, was removed.
* WikiPage::prepareContentForEdit() now requires a UserIdentity parameter to be
  provided. Not providing one has been deprecated since 1.37.
* EventRelayerKafka, deprecated in 1.38, was removed.
* MediaWiki\Logger\Monolog\KafkaHandler, deprecated in 1.38, was removed.
* The "trace" option of SectionProfiler, deprecated in 1.38, was removed.
* The global function wfWikiID(), deprecated since 1.35, has been removed.
* Database::wasKnownStatementRollbackError() was removed. Subclasses should
  override isKnownStatementRollbackError() instead.
* Database::wasQueryTimeoutError() was removed. Subclasses should
  override isQueryTimeoutError() instead.
* Database::buildSuperlative() has been removed without deprecation.
* The following methods, deprecated in 1.37, have been removed:
  - Linker::setStubThreshold(), ::getStubThreshold().
  - LinkRendererFactory::createForUser().
  - ParserOptions::getStubThreshold(), ::setStubThreshold().
* Changes to ResourceLoader modules:
  - The mediawiki.viewport module, deprecated in 1.37 has been
     removed. Use IntersectionObserver instead.
* If you manage a wiki in Swahili, and you use "Faili:" as a namespace anywhere,
  and you mean to use it as "Media:", replace it with "Media:". See T304920.
* Changes to skins:
  - Skin::getCopyrightIcon(), ::getPoweredBy(), deprecated in 1.37 have been
    removed.
  - Skin::bottomScripts, deprecated in 1.37, now emits deprecation notices.
    Skins using SkinTemplate must set bodyOnly as a skin option and
    remove lines of code generating html, body and head elements.
  - Skin::makeSearchButton and Skin::makeSearchInput were deprecated in 1.38.
    Use SkinTemplate methods with the same name or Skin::getTemplateData
    instead.
  - Styles for the HTML classes `warningbox`, `errorbox` and `successbox` have
    been removed in favor of Html class methods.
  - The feature `legacy` used inside ResourceLoaderSkinModule,
    deprecated in 1.37, will no longer ship any styles.
  - Skin::getSkinStylePath, deprecated since 1.36, has been removed.
  - Skin::getPortletData has been made private.
  - SkinTemplate::getPersonalToolsList(), deprecated in 1.35 has been
    removed.
  - The following SkinTemplate template data, deprecated in 1.37,
    have been removed:
     - poweredbyico
     - copyrightico
  - The following hooks, deprecated in 1.37, have been removed:
     - SkinGetPoweredBy: SkinGetPoweredByHook
  - The following hooks are deprecated and replaced with
    SkinTemplateNavigation::Universal:
     - SkinTemplateNavigation::SpecialPage
     - SkinTemplateNavigation
     - PersonalUrls
  - The mediawiki.skinning.content.externallinks module, which was
    deprecated in 1.36 has been removed. Skins that still rely on it
    will lose the icon styling of external links by type.
* Experimental wiki farm support: Automatic detection of the requested site
  within a wiki farm based on the requested domain has been removed.
  Use the MW_WIKI_NAME environment variable to specify the name of the site
  to load configuration for. Using the WIKI_NAME environment variable for this
  purpose is deprecated. This is only relevant if you have been using
  $wgWikiFarmSettingsDirectory to load wiki farm config.
* MWExceptionHandler::installHandler was marked @internal and had required
  arguments added. This method is intended for use in bootstrap code and is
  unused in known extensions.
* MWException::useOutputPage was made private without deprecation.
  This method was apparently only public for testing and is unused in known
  extensions.
* Calling getId() on a User or UserIdentityValue from the wrong wiki, deprecated
  since 1.36, now throws an exception.
* The following methods have been removed from ExtensionRegistry without
  deprecation and without replacement. They had been introduced in 1.35 for use
  in the testing framework, and were not in use by any known extension:
  - exportAutoloadClassesAndNamespaces
  - exportTestAutoloadClassesAndNamespaces
* The MWNamespace class, deprecated since 1.34, has been removed. Use the
  NamespaceInfo service instead.
* The UnknownContent and UnknownContentHandler class aliases have been removed,
  use FallbackContent and FallbackContentHandler instead.
* IResultWrapper::next() now returns void, to match the Iterator interface that
  it implements. fetchObject() has the same behavior as next() used to.
* In HTMLForm HTMLAutoCompleteSelectFields, the parameters 'autocomplete' and
  'autocomplete-messages', which were deprecated in MediaWiki 1.29, were
  removed. Instead, use 'autocomplete-data' and 'autocomplete-data-messages'.
* The global $wgParser, deprecated in 1.32, was removed. Use
  MediaWikiServices::getInstance()->getParser() instead.
* ParserOutput::setText will now set the ParserOutput's text to null if
  given null. Previously it did nothing if given null.
* The default value for the first argument to the ParserOutput constructor
  is now null instead of ''.
* IDatabase::lockTables() and IDatabase::unlockTables(), deprecated since 1.38,
  have been removed.
* The $context parameter to `new HTMLForm( … )` and `HTMLForm::factory( … )`
  is now required.
* The class alias for revision related classes in namespace MediaWiki\Storage
  has been removed. Classes are IncompleteRevisionException,
  MutableRevisionRecord, MutableRevisionSlots, RevisionAccessException,
  RevisionArchiveRecord, RevisionFactory, RevisionLookup, RevisionRecord,
  RevisionSlots, RevisionStore, RevisionStoreRecord, SlotRecord, and
  SuppressedDataException.
* Calling getBy() on an AbstractBlock from the wrong wiki, deprecated since
  1.38, now throws an exception.
* Passing a MediaWiki\Linker\LinkTarget to EditPage::makeTemplatesOnThisPageList
  or TemplatesOnThisPageFormatter::format is no longer supported,
  a MediaWiki\Page\PageIdentity is required.
* The deprecated class alias FakeConverter has been removed, use
  TrivialLanguageConverter instead.
* The deprecated ApiQueryContributions class alias has been removed, use
  ApiQueryUserContribs instead.
* The deprecated MediaWiki\Special\SpecialPageFactory class alias has been
  removed, use MediaWiki\SpecialPage\SpecialPageFactory instead.
* The following skin modules, deprecated in 1.37, have been removed:
	- mediawiki.skinning.elements
	- mediawiki.skinning.content
	- mediawiki.toc.styles
	- mediawiki.legacy.config
	- mediawiki.legacy.shared
	- mediawiki.legacy.commonPrint
* FileModule::compileLessFile(), deprecated since 1.35, has been removed. Use
  ::compileLessString() instead.
* LogFormatter::styleRestricedElement(), deprecated since 1.37, has been
  removed. Use ::styleRestrictedElement() instead.
* Title::isNamespaceProtected(), deprecated in 1.34, has been removed.
* ApiStashEdit::parseAndStash(), deprecated in 1.34, has been removed.
* LinkCache::forUpdate(), deprecated in 1.34, has been removed.
* Passing null instead of a NamespaceInfo instance to LinkCache::__construct()
  is not supported anymore. It is recommended to request an instance from the
  service container.
* ApiQueryBase::showHiddenUsersAddBlockInfo(), deprecated in 1.34, has been
  removed. Use ApiQueryBlockInfoTrait instead.
* ApiQueryBase::prefixedTitlePartToKey(), deprecated in 1.35, has been removed.
  Use ::parsePrefixedTitlePart() instead.
* ExternalStoreDB::getSlave(), deprecated in 1.34, has been removed. Use
  ExternalStoreDB::getReplica() instead.
* ChangesListSpecialPage::checkStructuredFilterUiEnabled() and
  SpecialWatchlist::checkStructuredFilterUiEnabled() now support UserIdentity
  as the only argument. Passing Config argument was deprecated in 1.34.
* DatabaseUpdater::ifNoActorTable(), deprecated in 1.35, has been removed. Use
  ::ifTableNotExists() instead.
* MediaWiki\Revision\RevisionStoreFactory::getRevisionStore was documented
  to allow passing bool true as a dbDomain, this is no longer possible,
  because that is an invalid value for a dbDomain.
* LinkHolderArray::__construct() had its signature changed. The class was marked
  internal in 1.35.
* SpecialMute::isTargetBlacklisted(), deprecated in 1.35, has been removed. Use
  ::isTargetMuted() instead.
* WebRequest::checkUrlExtension(), deprecated in 1.35, has been removed.
* ContentHandler::cleanupHandlersCache(), deprecated in 1.35, has been removed.
* SpecialVersion::getExtAuthorsFileName, deprecated in 1.35, has been removed.
  Use MediaWiki\ExtensionInfo::getAuthorsFileName.
* SpecialVersion::getExtLicenseFileName, deprecated in 1.35, has been removed.
  Use MediaWiki\ExtensionInfo::getLicenseFileNames.
* CategoryPage::getCategoryViewerClass and ::setCategoryViewerClass, deprecated
  in 1.35, have been removed.
* SqlBlobStore::getLegacyEncodingConversionLang(), deprecated in 1.34, has been
  removed.
* wfCanIPUseHTTPS(), deprecated in 1.37, has been removed.
* wfGetScriptUrl(), deprecated in 1.35, has been removed.
* The following methods of Database class, are no longer stable to override:
  - ::implicitOrderby()
  - ::selectSQLText()
  - ::bitNot()
  - ::bitAnd()
  - ::bitOr()
  - ::buildConcat()
  - ::buildGreatest()
  - ::buildLeast()
  - ::buildSubstring()
  - ::buildStringCast()
  - ::buildIntegerCast()
  - ::tableName()
  - ::addIdentifierQuotes()
  - ::buildLike()
  - ::limitResult()
  - ::unionSupportsOrderAndLimit()
  - ::unionQueries()
  - ::conditional()
  - ::strreplace()
  - ::timestamp()
  - ::getInfinity()
  - ::setTableAliases()
  - ::setIndexAliases()
  - ::buildGroupConcatField()
* SpecialUnblock::processUnblock(), deprecated in 1.36, has been removed. Use
  UnblockUser instead.
* wfLocalFile() and wfFindFile(), deprecated in 1.34, have been removed.
* Maintenance script resetUserTokens.php, deprecated in 1.27, has been removed.
* These methods in Database have been removed without deprecation as they are
  not used outside core. Users should override corresponding methods in
  SQLPlatform instead:
  - Database::doInsert -> SQLPlatform::insertSqlText
  - Database::doDropTable -> SQLPlatform::dropTableSqlText
  - Database::doRollback -> SQLPlatform::rollbackSqlText
  - Database::doSavepoint -> SQLPlatform::savepointSqlText
  - Database::doReleaseSavepoint -> SQLPlatform::releaseSavepointSqlText
  - Database::doRollbackToSavepoint -> SQLPlatform::rollbackToSavepointSqlText
* The following protected methods of Database class have been removed without
  deprecation as they are not used outside core. Users should call
  corresponding methods in SQLPlatform:
  - Database::makeInsertLists -> SQLPlatform::makeInsertLists
  - Database::isFlagInOptions -> SQLPlatform::isFlagInOptions
  - Database::normalizeOptions -> SQLPlatform::normalizeOptions
  - Database::fieldNameWithAlias -> SQLPlatform::fieldNameWithAlias
  - Database::isTransactableQuery -> SQLPlatform::isTransactableQuery
* $wgCanonicalNamespaceNames no longer includes custom namespaces defined using
  $wgExtraNamespaces. Extensions should use the NamespaceInfo service instead
  of accessing this configuration setting directly.
* The following hook, deprecated in 1.35, has been removed:
     - ParserGetVariableValueVarCache: ParserGetVariableValueVarCacheHook
* The $variableCache parameter to the ParserGetVariableValueSwitch hook is
  no longer used; non-standard use of this parameter has been deprecated since
  1.35.
* These methods have been moved from IDatabase to IMaintainableDatabase:
  - IDatabase::fieldExists -> IMaintainableDatabase::fieldExists
  - IDatabase::indexExists -> IMaintainableDatabase::indexExists
  - IDatabase::tableExists -> IMaintainableDatabase::tableExists
* DBConnRef doesn't accept live connection in constructor anymore.
  Only parameters for getting connection should be provided.
* IDatabase::getTopologyRootPrimary() was removed.
* User::blockedBy(), deprecated since 1.38, has been removed.
* User::getBlockId(), deprecated since 1.38, has been removed.

=== Deprecations in 1.39 ===
* PageProps::getInstance(), deprecated since 1.38, emits deprecations warnings.
* The global function wfGetDB() has been deprecated. Use
  LoadBalancer::getConnection() instead.
* SpecialRedirectWithAction::__construct without SearchEngineFactory argument
  will now emit a deprecation notice.
* Use of the SiteStatsUpdate constructor has been deprecated in favor of
  the ::factory() method.
* AuthManager::checkAccountCreatePermissions has been deprecated. Use
  AuthManager::authorizeCreateAccount or AuthManager::probablyCanCreateAccount
  instead.
* Title::getSelectFields() has been deprecated in favor of
  PageStore::newSelectQueryBuilder()
* Title::newFromTitleValue(), deprecated since in 1.34, now emits deprecation
  warnings. Use ::newFromLinkTarget() instead.
* ExtensionRegistry::readFromQueue() has been marked @internal. Extensions
  should use ExtensionProcessor instead.
* Processor::getExtraAutoloaderPaths() and
  ExtensionProcessor::getExtraAutoloaderPaths() have been deprecated, use get
  getExtractedAutoloadInfo() instead.
* The following global functions are deprecated in favor of the listed UrlUtils
  methods.
  - wfExpandUrl -> UrlUtils::expand
  - wfGetServerUrl -> UrlUtils::getServer
  - wfAssembleUrl -> UrlUtils::assemble
  - wfRemoveDotSegments -> UrlUtils::removeDotSegments
  - wfUrlProtocols -> UrlUtils::validProtocols
  - wfUrlProtocolsWithoutProtRel -> UrlUtils::validAbsoluteProtocols
  - wfParseUrl -> UrlUtils::parse
  - wfExpandIRI -> UrlUtils::expandIRI
  - wfMatchesDomainList -> UrlUtils::matchesDomainList
  These methods are exact replacements except that
  1) they return null instead of false or empty string on error (where
     applicable);
  2) UrlUtils::validProtocols does not take a parameter (documentation said not
     to pass one to wfUrlProtocols anyway);
  3) they use type hints (don't try passing null instead of string, etc.).
* MaintainableDBConnRef is deprecated, use DBConnRef instead.
* Loading DefaultSettings.php is deprecated. To get default values of main
  config settings, use MainConfigSchema::listDefaultValues() or
  MainConfigSchema::getDefaultValue().
* AbstractContent::getRedirectChain() and
  AbstractContent::getUltimateRedirectTarget() are now emitting deprecation
  warnings (T296430).
* (T244138) QueryPage::getSQL() is deprecated. Instead QueryPage::getQueryInfo()
  should be overridden.
* Calling new JobRunner() directly without $serviceOptions now emits
  deprecation warnings. Use MediaWikiServices::getInstance()->getJobRunner()
  instead.
* Passing an array of targets to Article::getRedirectHeaderHtml() is
  deprecated. Supply a single redirect target instead (T296430).
* The following Less mediawiki.mixins have been deprecated:
  - .animation()
  - .animation-delay()
  - .transform-rotate()
* Skin::getAction is deprecated. Use IContextSource::getActionName instead.
* User::getOption, deprecated since 1.35, now emits deprecation warnings.
  Use UserOptionsLookup::getOption instead.
* ILBFactory::forEachLB() is deprecated. Use ::getAllLBs().
* LoadBalancer::forEachOpenConnection() and ::forEachOpenPrimaryConnection()
  are deprecated without replacement.
* The following classes were moved from the root namespace to the
  MediaWiki\ResourceLoader namespace, the old names becoming deprecated aliases:
  ResourceLoader, MessageBlobStore, VueComponentParser.
* The following classes had the "ResourceLoader" prefix stripped while being
  moved to the MediaWiki\ResourceLoader namespace, the old names becoming
  deprecated aliases: DerivativeResourceLoaderContext,
  ResourceLoaderCircularDependencyError, ResourceLoaderClientHtml,
  ResourceLoaderCodexModule, ResourceLoaderContext, ResourceLoaderFileModule,
  ResourceLoaderFilePath, ResourceLoaderForeignApiModule, ResourceLoaderImage,
  ResourceLoaderImageModule, ResourceLoaderLanguageDataModule,
  ResourceLoaderLessVarFileModule, ResourceLoaderModule,
  ResourceLoaderMwUrlModule, ResourceLoaderOOUIFileModule,
  ResourceLoaderOOUIIconPackModule, ResourceLoaderOOUIImageModule,
  ResourceLoaderOOUIModule, ResourceLoaderSiteModule,
  ResourceLoaderSiteStylesModule, ResourceLoaderSkinModule,
  ResourceLoaderStartUpModule, ResourceLoaderUserModule,
  ResourceLoaderUserOptionsModule, ResourceLoaderUserStylesModule,
  ResourceLoaderWikiModule.
* The following methods in WikiRevision and their interfaces
  ImportableUploadRevision and ImportableOldRevision are deprecated:
  - ::getUserObj() → ::getUser()
  - ::setUserObj() → ::setUsername()
  - ::setUserIP() → ::setUsername()
* ObjectCache::addBusyCallback() is deprecated and non-functional.
* MWTimestamp::getHumanTimestamp(), deprecated in 1.26, now emits deprecation
  warnings.
* Article::viewRedirect(), deprecated in 1.30, now emits deprecation warnings.
* Parser::getFreshParser() is deprecated, use ParserFactory::getInstance().
* CoreParserFunctions::mwnamespace() is deprecated and emits deprecation
  warnings, use CoreParserFunctions::namespace() instead.
* Registering magic variables whose names include a colon is deprecated.
* User::blockedFor(), deprecated in 1.35, now emits deprecation warnings.
* Access to previously public properties AbstractBlock::$mExpiry,
  AbstractBlock::$mHideName, AbstractBlock::$mTimestamp, DatabaseBlock::$mAuto,
  and DatabaseBlock::$mParentBlockId, deprecated in 1.34, now emits deprecation
  warnings.
* Access to previously public properties User::$mBlock, User::$mBlockedby, and
  User::$mHideName, deprecated in 1.35, now emits deprecation warnings.
* JobQueueGroup::singleton() and ::destroySingletons(), deprecated in 1.37, now
  emit deprecation warnings.
* Title::getNotificationTimestamp(), deprecated in 1.35, now emits deprecation
  warnings.
* Global functions wfReadOnly and wfReadOnlyReason, deprecated in 1.38, now
  emit deprecation warnings.
* Overriding or calling DifferenceEngine::getDiffBodyCacheKey(), deprecated in
  1.31, now emits deprecation warnings.
* Access to previously public property WikiRevision::$fileIsTemp, deprecated in
  1.29, now emits deprecation warnings.
* wfQueriesMustScale() has been deprecated and emits deprecation warnings.
* ContextSource::getStats(), RequestContext::getStats(), and
  DerivativeContext::getStats(), deprecated in 1.27, now emit deprecation
  warnings.
* ManualLogEntry::setTags(), deprecated in 1.33, now emits deprecation warnings.
* WikiRevision::downloadSource(), deprecated in 1.31, now emits deprecation
  warnings.
* DifferenceEngine::textDiff(), deprecated in 1.32, now emits deprecation
  warnings.
* FormatMetadata::flattenArrayContentLang(), deprecated in 1.36, now emits
  deprecation warnings.
* SkinTemplate::getNameSpaceKey(), deprecated in 1.35, now emits deprecation
  warnings.
* EnqueueJob::newFromJobsByWiki(), deprecated in 1.33, now emits deprecation
  warnings.
* The following methods of the MWGrants class, all deprecated since 1.38,
  are now emitting deprecation warnings:
  - getValidGrants
  - getRightsByGrant
  - grantName
  - grantNames
  - getGrantRights
  - grantsAreValid
  - getGrantGroups
  - getHiddenGrants
  - getGrantsLink
  - getGrantsWikiText
* DataUpdate::runUpdates(), deprecated in 1.28, now emits deprecation warnings.
* CdnCacheUpdate::newFromTitles(), deprecated in 1.35, now emits deprecation
  warnings.
* Instantiating HTMLCacheUpdate class, deprecated in 1.34, now emits deprecation
  warnings.
* ISQLPlatform::tableNames() (implemented by IDatabase) is now deprecated.
  None of the tableName*() functions should be used by most users;
  if you absolutely must use raw SQL, write several tableName() calls instead.
* Language::isWellFormedLanguageTag() has been deprecated in favor of
  LanguageCode::isWellFormedLanguageTag().
* The PrevNextNavigationRenderer helper class has been deprecated in favor of
  the new PagerNavigationBuilder one.
* The methods IndexPager::getPagingLinks(), IndexPager::getLimitLinks() and
  IndexPager::buildPrevNextNavigation() have been deprecated in favor of
  IndexPager::getNavigationBuilder().
* Overriding the method IndexPager::makeLink() has been deprecated.
* ActorMigration is deprecated. The temporary table is no longer needed, the
  actor table can be directly joined to the revision table, which is simple
  enough to not need a helper class. See the methods of ActorMigration for more
  specific information on replacements. ActorMigrationBase remains usable for
  migrations in extension tables.
* …

=== Other changes in 1.39 ===
* Dynamic default values are now applied before extension registration callbacks
  are run. This way, extensions have a complete view of config variables, with
  all defaults applied. For example, when the default value of X used to be
  static but becomes dynamic, and an extension reads the value of X in the
  registration callback, it will now continue to function as expected. In some
  cases however, this may cause an undesired change in behavior: if the dynamic
  default of setting X depends on the value of setting Y, and an extension
  changes Y, the changed value of Y will no longer affect the value of X.

== Compatibility ==

MediaWiki 1.39 requires PHP 7.4.3 or later and the following PHP extensions:

* ctype
* dom
* fileinfo
* iconv
* intl
* json
* mbstring
* xml

MariaDB is the recommended database software. MySQL, PostgreSQL, or SQLite can
be used instead, but support for them is somewhat less mature.

The supported versions are:

* MariaDB 10.3 or higher
* MySQL 5.7.0 or higher
* PostgreSQL 10 or later
* SQLite 3.8.0 or later

== Online documentation ==
Documentation for both end-users and site administrators is available on
MediaWiki.org, and is covered under the GNU Free Documentation License (except
for pages that explicitly state that their contents are in the public domain):

       https://www.mediawiki.org/wiki/Special:MyLanguage/Documentation

== Mailing list ==
A mailing list is available for MediaWiki user support and discussion:

       https://lists.wikimedia.org/mailman/listinfo/mediawiki-l

A low-traffic announcements-only list is also available:

       https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce

It's highly recommended that you sign up for one of these lists if you're
going to run a public MediaWiki, so you can be notified of security fixes.

== IRC help ==
There's usually someone online in #mediawiki on irc.libera.chat.