Release notes/1.38

= MediaWiki 1.38 =

MediaWiki 1.38.2
This is a security and maintenance release of the MediaWiki 1.38 branch.

Changes since MediaWiki 1.38.1

 * Localisation updates.
 * (T309426) Repair language selector for SVGs.
 * (T310013) Fix default value for $wgShowEXIF and $wgUsePathInfo.
 * (T308471) SECURITY: Escape welcomeuser message passed to showSuccessPage.
 * (T308473) SECURITY: Escape contributions-title msg for use within page title.
 * (T311272) Call parent constructor of AddSite maintenance script first.
 * MediaWiki: Don't eagerly initialize action name.
 * (T311384, CVE-2022-27776) Updated guzzlehttp/guzzle from 7.4.1 to 7.4.5.
 * (T289926) Avoid passing null to trim in SkinTemplate.
 * (T289879) Address deprecations for PHP 8.1.
 * (T311473) rollbackEdits: Pass user identity to RollbackPage.
 * Upgrade wikimedia/remex-html from 3.0.1 to 3.0.2.
 * (T311551) ShellboxClientFactory::getUrl: Check if $this->key is null.
 * (T311552) ChangesListSpecialPage: Don't pass null to FormatJson::decode.
 * (T311569) FileBackend::isStoragePath Handle being passed null.
 * (T311544) Pass int to ApiUsageException::newWithMessage's $httpCode param.
 * (T311678) SpecialEditWatchlist: Prevent passing null to strtolower.
 * (T311554) ChangeTags: Return early in formatSummaryRow if $tags === null.
 * Upgrade wikimedia/common-passwords from 0.3.0 to 0.4.0.

MediaWiki 1.38.1
This is a maintenance release of the MediaWiki 1.38 branch.

Changes since MediaWiki 1.38.0

 * (T309860) Add justinrainbow/json-schema to vendor.
 * (T309933) Drop PHP 7.2 support in MediaWiki 1.38; require 7.3.19.

Changes since MediaWiki 1.38.0-rc.1

 * Localisation updates.
 * (T309114) LocalFile::prerenderThumbnails: Limit the number of thumbnail jobs triggered.


 * (T305779) phpunit: Support setting skin context in BundleSizeTest subclasses.
 * (T309028) SECURITY: ApiEditPage: update title after redirects.
 * (T308967) notifications: prevent log spam when invalid user object listed.
 * composer: Lock Parsoid version to specific 0.15.0 release.
 * (T306362, T308680) change-your-logo.svg: Resize to 135px square, re-crush, and manually minify.

Changes since MediaWiki 1.38.0-rc.0

 * Localisation updates.
 * (T305028) Undeprecate EditPage::$textbox2.
 * (T305635) LogActions is a map, not a list.
 * (T306721) Add wikimedia/equivset to vendor; needed by bundled AbuseFilter.
 * (T307284) Simplify TransactionManager::pendingWriteQueryDuration.
 * (T307307) Add symfony/yaml to vendor.
 * Fix old_name in UserLogoutComplete hook.
 * REST: don't send stack trace in error responses.
 * (T307998) SessionManager: stop storing an ObjectFactory instance.
 * (T193565) UserGroupManager: Fix dbDomain in addUserToGroup deferred update.

Upgrading notes for 1.38
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 1.29.

Some specific notes for MediaWiki 1.38 upgrades are below:
 * (T191740) The AbuseFilter extension is now bundled with MediaWiki. This is an anti-abuse feature that lets privileged users to set specific actions to be taken when actions by users, such as edits or file uploads, match certain criteria.
 * (T232948) The Math extension is now bundled with MediaWiki. This is a content feature that lets users create mathematical formulæ, written in a sub-set of LaTeX and rendered in MathML with a fallback SVG image. By default, it will use Wikimedia's mathoid service to render each formula, but local rendering can be set up for network isolation or performance.
 * (T191743) The Minerva skin is now bundled with MediaWiki. This is a simple, light-weight, and scalable skin that is particularly optimised for mobile use, and integrates well with the MobileFrontend extension (available separately), but can also be used as a regular desktop skin.

For notes on 1.37.x and older releases, see HISTORY.

New configuration

 * (T297708) $wgMaxExecutionTimeForExpensiveQueries - This setting can be used to control the maximum execution time for several expensive query pages (e.g. RecentChanges and UserContribs).
 * $wgBrowserFormatDetection – This setting allows overriding browsers' automatic detection and handling of formats. It's initially used to prevent auto-linking of possible telephone numbers in wiki pages' output in Safari on iOS; this can be re-enabled if you wish, or locally extended for other browsers' quirks.
 * (T240685) $wgMetricsTarget, $wgMetricsFormat, $wgMetricsPrefix - These provide configuration for a new MetricsFactory service with support for the dogstatsd format, intended for integration with Prometheus integration.
 * $wgGroupInheritsPermissions – This setting allows inheriting permissions, both granted and revoked, from another group.
 * $wgForeignApiRepos – ForeignAPIRepo now has a apiMetadataExpiry option to control for how long file metadata is cached. Additionally the default changed from 1 hour to 4 hours.
 * $wgSkinsPreferred – This lets you set a list of preferred skins to be listed higher in Special:Preferences.
 * $wgWikiFarmSettingsDirectory – A directory that contains site-specific configuration files. Setting this will enable multi-tenant ("wiki farm") mode, causing site-specific settings to be loaded based on information from the web request. EXPERIMENTAL.
 * $wgWikiFarmSettingsExtension – The file extension to be used when looking up site-specific settings files in $wgWikiFarmSettingsDirectory, such as 'json' or 'yaml'. EXPERIMENTAL.
 * $wgWikiFarmSiteDetector – A callback function that returns the name of the wiki for the current request. This is used in multi-tenant ("wiki farm") mode to determine which settings file to load from $wgWikiFarmSettingsDirectory. EXPERIMENTAL.
 * $wgEnableRemoteBagOStuffTests – This replaces the environment variable PHPUNIT_USE_BAGOSTUFF.
 * (T230211) $wgForceDeferredUpdatesPreSend – Force deferred updates to be run before sending a response to the client, instead of attempting to run them after sending the response. Setting this to true is useful for end-to-end testing, to ensure that the effects of a request are visible to any subsequent requests, even if they are made immediately after the first one. Note however that this does not ensure that database replication is complete, nor does it execute any jobs enqueued for later.
 * $wgTemplateLinksSchemaMigrationStage – Templatelinks table schema migration stage, for normalizing tl_namespace and tl_title fields.

Changed configuration

 * $wgStyleDirectory and $wgExtensionDirectory – These are now set later, so can no longer be used within LocalSettings.php unless explicitly set in that file.
 * $wgFileBackends – This setting no longer takes 'fileJournal' as an option.
 * $wgMaxImageArea - This setting may now be set to false to disable size, checking before scaling. Extensions can still override its value by using the BitmapHandlerCheckImageArea hook.
 * $wgAjaxUploadDestCheck – This is now deprecated, and act as always-true.
 * $wgInterwikiCache – This no longer supports the string value for CDB files.
 * $wgParserOutputHooks – This is now deprecated; adjustments using this should be done with OutputPageParserOutputHook instead. (T292321)
 * $wgExternalStores – This is newly documentated in includes/externalstore/README.md.

Removed configuration

 * $wgShellLocale - This setting has been removed as it was a flawed solution to the problem of locale dependence, MediaWiki will now always set a locale of C.UTF-8 or C and works around the remaining problems of the C locale by not using escapeshellarg. This follows the direction of PHP 8.0, which sets a locale of C by default instead of respecting LC_CTYPE.
 * $wgLoggedOutMaxAge - Experiment removed, originally added in 1.35. (T293848)
 * $wgIncludejQueryMigrate - Deprecated in 1.36. We only support jQuery v3.
 * $wgUseCategoryBrowser - This experimental feature has been removed. If you still need to use this feature, please see mw:Extension:CategoryExplorer.
 * $wgStyleSheetPath - alias for $wgStylePath, deprecated since 1.3 (2004).

User-facing changes in 1.38

 * (T284921) The "auto-number headings" feature was removed following a consultation, due to performance reasons.

New operator/developer features in 1.38
Settings for each site can be placed in a directory specified by $wgWikiFarmSettingsDirectory. Site detection is controlled by $wgWikiFarmSiteDetector and defaults to the requested host name. For example, setting $wgWikiFarmSettingsDirectory = "sites" would cause the settings for wiki.example.com to be loaded from "sites/wiki_example_com.yaml". WARNING: YAML files under the web root may be accessible to browsers, please take appropriate measures to protect them from access via HTTP.
 * EXPERIMENTAL: The environment variable MW_CONFIG_FILE can be used to specify the location of the settings file. This allows alternative settings files to be loaded depending on the environment. Settings files may be given as PHP files like the traditional LocalSettings.php file, or they may use JSON or YAML format. See https://www.mediawiki.org/wiki/Manual:YAML_settings_file_format
 * Added a deleteUserEmail maintenance script - This file enables the deletion of a given user's associated email address. It can be helpful for privacy-preserving operations.
 * The description array for constructing an HTMLForm now can use 'disable-if' to disable fields on condition easily, supported expressions are the same as 'hide-if'.
 * There is a new interface, IForeignRepoWithMWApi, to allows you to mark file repos provided by an extension as supporting making API queries against the foreign file repo so that extensions like TimedMediaHandler that depend on this can stop hard-coding looking for specific class names.
 * Added EXPERIMENTAL support for an easy to configure multi-tenant ("wiki farm") mode:
 * Running QUnit tests for an individual test suite module is possible with `grunt qunit --qunit-component={componentName}`, where {componentName} is "MediaWiki" to run core's QUnit tests or the skin or extension name.
 * The 'mediawiki.mixins' module now has a `.user-select` Less mixin.

New external libraries

 * symfony/yaml was promoted from development-only.

Changed external libraries

 * Updated OOUI from v0.42.0 to v0.43.2.
 * Updated Vue from 2.6.11 to 3.2.23.
 * Updated WVUI from v0.3.0 to v0.4.0.
 * Updated composer/semver from 3.2.5 to 3.2.6.
 * Updated guzzlehttp/guzzle from 7.2.0 to 7.4.1.
 * Updated pear/mail_mime from 1.10.9 to 1.10.11.
 * Updated pear/net_smtp from 1.9.2 to 1.10.0.
 * Updated psr/log from 1.1.3 to 1.1.4.
 * Updated psy/psysh from 0.10.5 to 0.11.1.
 * Updated symfony/polyfill-php80 from 1.23.1 to 1.25.0.
 * Updated wikimedia/assert from 0.5.0 to 0.5.1.
 * Updated wikimedia/cdb from 1.4.1 to 2.0.0.
 * Updated wikimedia/ip-utils from 3.0.2 to 4.0.0.
 * Updated wikimedia/minify from 2.2.4 to 2.2.6.
 * Updated wikimedia/object-factory from 3.0.2 to 4.0.0.
 * Updated wikimedia/parsoid from v0.14.0-a14 to v0.15.0.
 * Updated wikimedia/purtle from 1.0.7 to 1.0.8.
 * Updated wikimedia/request-timeout from 1.1.0 to 1.2.0.
 * Updated wikimedia/shellbox from 2.0.0 to 3.0.0.
 * Updated wikimedia/wrappedstring from 3.2.0 to 4.0.1.

Changed development-only external libraries

 * Updated QUnit from 2.16.0 to 2.18.0.
 * Updated composer/semver from 3.5.4 to 3.5.5.
 * Updated composer/spdx-licenses from 1.5.4 to 1.5.5.
 * Updated doctrine/dbal for PHP < 7.3 from 2.10.4 to 2.13.6.
 * Updated doctrine/dbal for PHP >= 7.3 from 3.0.0 to 3.1.5.

Removed external libraries

 * jquery.jStorage, deprecated since MW 1.28; use "mediawiki.storage" instead.

Action API changes in 1.38

 * New `deletetalk` parameter on action=delete that allows you to delete the associated talk page of a subject page.
 * New `variant` parameter for all API actions, for specifying language variant (akin to the existing `variant` parameter for index.php). Task T117549.

Languages updated in 1.38
MediaWiki supports over 400 languages. Many localisations are updated regularly. Below only new and removed languages are listed, as well as changes to languages because of Phabricator reports.


 * (T292166) Updated namespace names for the Lombard language.
 * (T299201) Changed the autonym of the Angika language to अंगिका
 * (T298309) Changed the autonym of the Abkhaz language to аԥсшәа
 * (T302972) Changed the autonym of the Kirundi language to ikirundi
 * (T220303) Show numbered lists with Burmese numerals in relevant languages
 * (T291899) Added language support for Xiang Chinese (hsn).
 * (T292612) Added language support for S'gaw Karen (ksw).
 * (T293656) Added language support for Farefare (gur).
 * (T294729) Added language support for Pa'O (blk).
 * (T296286) Added language support for Skolt Sámi (sms).
 * (T296612) Added language support for Makhuwa (vmw).
 * (T296707) Added language support for Ga (gaa).
 * (T297073) Added language support for Nanai (gld).
 * (T297074) Added language support for Nawdm (nmz).
 * (T298075) Added language support for Northern Thai (nod).
 * (T298182) Added language support for Cape Verdean Creole (kea).
 * (T298385) Added language support for Nheengatu (yrl).
 * (T299329) Added language support for Fon (fon).
 * (T300474) Added language support for Nkore (nyn).
 * (T302556) Added language support for Pannonian Rusyn (rsk).

Breaking changes in 1.38
- ::__construct (the class is no longer newable) - ::execute - ::haveDeletableFile Use FileDeleteAction instead. - $wgCookiePrefix - $wgCookieDomain - $wgCookiePath - $wgCookieExpiration Use mw.cookie from the mediawiki.cookie module instead. - Skin::privacyLink - Skin::aboutLink - Skin::disclaimerLink For these, instead use Skin::footerLink to alter footer links. - Skin::getLogo For this, use ResourceLoaderSkinModule::getAvailableLogos instead. - Skin::getIndicatorsHTML For this, use Skin::getIndicatorsData instead. - Skin::subPageSubtitle For this, use Skin::prepareSubtitle instead. - Skin::makeVariablesScript For this, use ResourceLoader::makeInlineScript instead. - Skin::getAllowedSkins - Skin::getSkinNames For these, use SkinFactory::getAllowedSkins or ::getInstalledSkins. - Skin::makeUrl - Skin::getSearchLink - Skin::mainPageLink - DatabaseBlock constructor 'byText' property with blocker's name, use 'by' property with UserIdentity value instead. - DatabaseBlock constructor 'by' property with blocker's ID, use 'by' property with UserIdentity value instead. - DatabaseBlock::isWhitelistedFromAutoblocks, use ::isExemptedFromAutoblocks. - DatabaseBlock::setBlocker now only accepts UserIdentity. - AbstractBlock::getTargetAndType and ::getTarget, use ::getTargetName, ::getTargetUserIdentity and ::getType instead - Title::isWatchable - WatchAction::doWatchOrUnwatch, WatchAction::doWatch, WatchAction::doUnwatch, WatchAction::getWatchToken - User::isWatched, User::isTempWatched, User::addWatch, User::removeWatch - ::resetIdByNameCache, - ::getStubThreshold, - ::matchEditTokenNoSuffix, - ::changeableByGroup, - ::changeableGroups, - ::isAllowUsertalk, - ::getRights - ::isAllowUsertalk - ::isIP, - ::isIPRange, - ::isValidUserName, - ::isUsableName, - ::isCreatableName, - ::getCanonicalName, - ::addAutopromoteOnceGroups, - ::getDefaultOptions, - ::getDefaultOption, - ::getOptions, - ::getBoolOption, - ::getIntOption, - ::setOption - ::listOptionKinds - ::getOptionKinds, - ::resetOptions, - ::getEffectiveGroups, - ::getAutomaticGroups, - ::getFormerGroups - ::isLoggedIn - ::getFirstEditTimestamp - ::getLatestEditTimestamp - ::preCommitCallbacksPending - ::pendingWriteRowsAffected - ::getServerUptime - ::maxListLen - ::aggregateValue soft-deprecated since 1.33 - ::getTopologyRootMaster since 1.37 - ::masterPosWait since 1.37 - ::dataSeek soft-deprecated since 1.37 - ::numFields soft-deprecated since 1.37 - ::fieldName soft-deprecated since 1.37 - ::onTransactionIdle soft-deprecated since 1.32 - ::getMasterPos since 1.37 - ::$mWeekdayMsgs → WEEKDAY_MESSAGES - ::$mWeekdayAbbrevMsg → WEEKDAY_ABBREVIATED_MESSAGES - ::$mMonthGenMsgs → MONTH_GENITIVE_MESSAGES - ::$mIranianCalendarMonthMsgs → IRANIAN_CALENDAR_MONTHS_MESSAGES - ::$mHebrewCalendarMonthMsgs → HEBREW_CALENDAR_MONTHS_MESSAGES - ::$mHebrewCalendarMonthGenMsgs → HEBREW_CALENDAR_MONTH_GENITIVE_MESSAGES - ::$mHijriCalendarMonthMsgs → HIJRI_CALENDAR_MONTH_MESSAGES - ::getCancelLink - ::isSupportedContentModel - ::getParentRevId - ::beginMasterChanges since 1.37 - ::commitMasterChanges since 1.37 - ::rollbackMasterChanges since 1.37 - ::hasMasterChanges since 1.37 - ::hasOrMadeRecentMasterChanges since 1.37 - ::waitForOne - ::allowLagged - ::forEachOpenReplicaConnection - ::getMasterPos since 1.37 - ::finalizeMasterChanges since 1.37 - ::approveMasterChanges since 1.37 - ::beginMasterChanges since 1.37 - ::commitMasterChanges since 1.37 - ::runMasterTransactionIdleCallbacks since 1.37 - ::runMasterTransactionListenerCallbacks since 1.37 - ::rollbackMasterChanges since 1.37 - ::flushMasterSnapshots since 1.37 - ::hasMasterConnection since 1.37 - ::hasMasterChanges since 1.37 - ::lastMasterChangeTimestamp since 1.37 - ::hasOrMadeRecentMasterChanges since 1.37 - ::pendingMasterChangeCallers since 1.37 - ::forEachOpenMasterConnection since 1.37 - ::waitForMasterPos since 1.37 - ::$deletedSinceEdit - ::$lastDelete - ::$mTokenOk - ::$mTriedSave - ::$incompleteForm - ::$tooBig - ::$missingComment - ::$missingSummary - ::$allowBlankSummary - ::$autoSumm - ::$mParserOutput - ::$hasPresetSummary - ::$minoredit - ::$watchthis - ::$recreate - ::$nosummaryparentRevId - ::$editintro - ::$scrolltop - ::$markAsBot
 * (T291008) The IP class, deprecated since 1.35 in favor of the IPUtils library, has been removed. The IP related regexes which were also deprecated in favor of the IPUtils library were also removed, IPUtils::RE_* should be used instead.
 * (T293043) The MediaWikiIntegrationTestCase class alias 'MediaWikiTestCase' has been removed.
 * LinkCache::singleton, deprecated since 1.28, has been removed.
 * RepoGroup::singleton, ::destroySingletons and setSingleton, all deprecated since 1.34, have been removed.
 * The following methods from FileDeleteForm were removed:
 * MessageCache::singleton, deprecated since 1.34, has been removed.
 * LockManagerGroup::singleton and ::destroySingletons, both deprecated since 1.34, have been removed.
 * FileBackendGroup::singleton and ::destroySingletons, both deprecated since 1.35, have been removed.
 * TemplateParser used to support disabling the cache with a boolean parameter in its constructor. This was deprecated in 1.35 and has now been removed.
 * The ArticleUndeleteLogEntry hook, deprecated in 1.37, was removed.
 * The BeforeResetNotificationTimestamp hook, deprecated in 1.37, was removed.
 * The global function mimeTypeMatch has been removed without a deprecation process.
 * The following JavaScript mw.config keys have been removed:
 * The signature of PageUpdater::markAsRevert method was changed. It has never been used outside of MediaWiki core.
 * If you want to use interwiki titles with HTMLTitleTextField, you now need to pass 'interwiki' => true. In 1.37, the default behavior was to let interwiki title through by default, logging a deprecation warning.
 * The `UndeleteForm::undelete` hook, deprecated in 1.37, was removed.
 * BagOStuff::setDebug, deprecated since 1.36, has been removed.
 * The `jquery.mw-jump` ResourceLoader module was removed.
 * The `wgForeignUploadTargets` and `wgEnableUploads` configuration values were removed from mw.config. They had previously been documented as being included for internal use by the mediawiki.ForeignUpload module.
 * The `&$hasHistory` parameter to WikiPage::getAutoDeleteReason and ContentHandler::getAutoDeleteReason was hard-deprecated with no replacement.
 * Several Skin methods, which have emitted deprecation warnings since 1.36, have been removed. These include:
 * Parser::getUser and ::mUser, as well as ParserOptions::getUser, deprecated since 1.37, has been removed.
 * Parser::$mStripState, deprecated in 1.35, has been made private. Use Parser::getStripState instead.
 * The following deprecated features in blocks were removed:
 * The following functions, emitting deprecations since 1.37, have been removed:
 * ParserOptions::setTidy that had no effect and was deprecated since 1.35 has been removed.
 * The "YAML" encoding option of EtcdConfig, has been removed without deprecation.
 * The constant ApiBase::PARAM_VALUE_LINKS, deprecated since 1.35 has been removed.
 * UserLoadOptions, UserSaveOptions and UserResetAllOptions hooks, deprecated since 1.37, were removed.
 * The experimental FileJournal system has been removed without deprecation. This includes the FileJournal abstract class, its implementation classes DBFileJournal and NullFileJournal, various minor getters and setters, and the option for the wiki configuration $wgFileBackends.
 * The return values for each `bind` function in checkboxHack.js has been changed from an object to a function. In addition, the `unbind` function has been removed. A deprecation process was assumed unnecessary as there were no known usages.
 * File::getUser, ::getImageSize, ArchivedFile::getRawDescription, ::getUser, ::getRawUser and ::getRawDescription, deprecated since 1.37, has been removed.
 * ShellboxHttpClient class has been removed without deprecation. It was an internal class used by ShellboxClientFactory.
 * The following hard deprecated User methods have been removed:
 * Http::$httpEngine, deprecated since 1.34, has been removed. The only available HTTP engine is now Guzzle. CurlHttpRequest and PhpHttpRequest classes were removed.
 * The UserRightsProxy class was deprecated. Pass the correct domain to UserGroupManagerFactory instead.
 * Parser option enableLimitReport was deprecated. The report is now generated post-parse and can be included by providing 'includeDebugInfo' option to ParserOutput::getText. Thus, ParserOptions::enableLimitReport and ::getEnableLimitReport methods were deprecated.
 * Ajax action that was deprecated in 1.27 now has been removed.
 * The following methods have been removed from IDatabase without deprecation as they were completely unused:
 * The following deprecated methods have been removed from IDatabase:
 * DatabaseMysqlBase::fieldType and DatabasePostgres::fieldType, deprecated since 1.37, have been removed.
 * Database::assertIsWritableMaster, deprecated since 1.37, has been removed.
 * ResultWrapper::getInternalResult, soft-deprecated since 1.37 and ResultWrapper::unwrap, deprecated since 1.37, have been removed.
 * Language::AS_AUTONYMS, deprecated since 1.34, has been removed. You can use the LanguageNameUtils::AUTONYMS constant instead.
 * Several Language class variables deprecated in 1.35 have been removed; they are each replaced by a constant, as listed after the arrow:
 * wfIncrStats, deprecated since 1.36, has been removed.
 * Profiler::profileIn and ::profileOut, deprecated in 1.33, has been removed.
 * IEditObject::AS_CANNOT_USE_CUSTOM_MODEL, deprecated in 1.35, was removed.
 * Several protected methods in EditPage were made private. None of these was used outside of EditPage itself. Since the class is not stable to extend, this change happened without a deprecation phase.
 * The following public methods in EditPage, unused externally, were made private:
 * EditPage::setApiEditOverride was marked as @internal for use by ApiEditPage only.
 * SelectQueryBuilder::straightJoin was renamed to straightJoinOption.
 * The following deprecated methods have been removed from ILBFactory:
 * The "groupLoadsByDB" option to LBFactoryMulti has been removed. Consider using "groupLoadsBySection" instead.
 * The following methods have been removed from ILoadBalancer without deprecation as they were completely unused:
 * The following deprecated methods have been removed from ILoadBalancer:
 * LoadBalancer::safeGetLag which has been soft-deprecated since 1.34 has been removed.
 * The following properties of the EditPage class, deprecated since 1.35, were made private:
 * Special:ListFiles and Special:NewFiles no longer allows to search for parts of file names (option was not available for $wgMiserMode = true)
 * DBAccessBase, deprecated since 1.37, has been removed.
 * The UserNamePrefixSearch service no longer supports a UserIdentity parameter to search, to check for a specific audience an Authority object is required.
 * The methods CoreParserFunctions::register and CoreTagHooks::register have been marked @internal, and had a seconds parameter added. These methods are intended for use in Parser's constructor, and are not used by any known extension.
 * LoadBalancer::openConnection, deprecated since 1.34, has been removed.
 * Skin::preloadExistence has been made private. There is no known usages outside of MediaWiki core.

Deprecations in 1.38
- Skin::setSearchPageTitle, Skin::getSearchPageTitle. For these, use SpecialPage::newSearchPage or associated user preference instead. - Skin::getSkinStylePath now triggers deprecation warnings. Direct string path should be used instead. - SkinTemplate::getPersonalToolsList, deprecated since 1.35, now emits deprecation warnings. - In preparation for SkinTemplate::getPortletData becoming a private function, extending the method is no longer permitted. Use SkinTemplate::getTemplateData instead. - SkinTemplate::buildContentNavigationUrls is now deprecated. Skins can use the runOnSkinTemplateNavigationHooks method or the SkinTemplateNavigation__Universal hook if they need access to this data. - searchaction, poweredbyico, copyrightico - ::blockedBy - ::getBlockId ParserOutput::{get,set}PageProperty('defaultsort') instead. - ::hideNewSection     - use ::setHideNewSection - ::preventClickjacking - use ::{get,set}PreventClickjacking - ::getProperty        - use ::getPageProperty (return value changed) - ::setProperty        - use ::setPageProperty - ::unsetProperty      - use ::unsetPageProperties - ::getProperties      - use ::getPageProperties - ::getCategoryLinks   - use ::getCategoryNames - ::setCategoryLinks   - use ::setCategories - ::addTrackingCategory - use Parser::addTrackingCategory or TrackingCategories::addTrackingCategory - ::addWarning         - use ::addWarningMsg - ::hasDynamicContent  - use ::hasReducedExpiry - ::getFlag - use ::getOutputFlag - ::setFlag - use ::setOutputFlag - ::getAllFlags - this method is now marked @internal - ::addJsConfigVars - use ::setJsConfigVar or ::appendJsConfigVar - ::addOutputHook / ::getOutputHooks - these hooks should be migrated to use the OutputPageParserOutput hook instead - ::addModules - if you formerly passed a string, pass an array with the string as the only element. - ::addModuleStyles - if you formerly passed a string, pass an array with the string as the only element. - ::$mCategoryLinks - ::$mCategories - ::$mIndicators - ::$mHeadItems - ::$mModules - ::$mModuleStyles - ::$mJsConfigVars - ::$mTemplateIds - ::$mEnableClientCache - ::$mNewSectionLink - ::$mHideNewSectionLink - ::$mNoGallery - OutputPage::preventClickjacking - OutputPage::allowClickjacking - ImageHistoryList::preventClickjacking - ImageHistoryPseudoPager::preventClickjacking - ContribsPager::preventClickjacking - isTalk - exists - subjectEquals - getCanonicalNamespaces - getCanonicalName - getCanonicalIndex - getValidNamespaces - isContent - hasSubpages - getContentNamespaces - Use UndeletePage instead of ::undeleteAsUser, ::getFileStatus and ::getRevisionStatus. - Use the respective methods of the new ArchivedRevisionLookup service instead of ::listRevisions, ::getRevisionRecordByTimestamp, ::getArchivedRevisionRecord, ::getPreviousRevisionRecord and ::getLastRevisionId. - Use ArchivedRevisionLookup::hasArchivedRevisions instead of ::isDeleted. - mArticle (use ::getArticle instead) - mTitle (use ::getTitle instead) - isNew (no replacement) - allowBlankArticle (no replacement) - selfRedirect (no replacement) - allowSelfRedirect (no replacement) - diff (no replacement) - textbox2 (no replacement) - undoAfter (no replacement) - edit (no replacement) - contentLength (no replacement) - .background-image - .list-style-image
 * The MWGrants class is deprecated in favor of the new GrantsInfo and GrantsLocalization services.
 * The global functions wfReadOnly and wfReadOnlyReason have been deprecated in favor of the ReadOnlyMode service.
 * PageProps::getInstance has been deprecated. Use MediaWikiServices::getPageProps instead.
 * User::setOption, deprecated since 1.35, now emits deprecation warnings.
 * Linker::formatComment, ::formatLinksInComment, ::commentBlock and revComment were deprecated. Use the new CommentFormatter service.
 * Several Skin methods have been deprecated.
 * Usage of several template data keys in QuickTemplate are now deprecated:
 * DatabaseBlock::purgeExpired, deprecated since 1.36, now emits deprecation warnings.
 * The following methods from the User class now trigger deprecation warnings:
 * Content::getParserOutput and AbstractContent::fillParserOutput was hard-deprecated, use ContentRenderer::getParserOutput instead. Extensions defining a content model should override ContentHandler::fillParserOutput.
 * Title::newFromIDs and TitleFactory::newFromIDs have been hard deprecated. Use a PageSelectQueryBuilder from a PageStore instead.
 * Content::getRedirectChain and Content::getUltimateRedirectTarget have been deprecated with no replacement because support for $wgMaxRedirect will be removed completely. See T296430 for more information.
 * WikiPage::getRedirectTarget has been deprecated. Use the equivalent RedirectLookup::getRedirectTarget instead.
 * Article::doDelete was deprecated. Use WikiPage::doDeleteArticleReal if you only need to delete the article. If you also need things to happen with OutputPage, you may want to check the hooks in DeleteAction instead.
 * Instantiating the MessageContent class now emits deprecation notices.
 * Message::content now triggers deprecation warnings.
 * Parser::setDefaultSort, Parser::getDefaultSort, and Parser::getCustomDefaultSort now trigger deprecation warnings. Use
 * The following methods from the ParserOutput class now emit deprecation warnings:
 * The following methods from the ParserOutput class were deprecated:
 * The use of ParserOutput::setExtensionData to overwrite previous values stored under a given key has been deprecated; use the new ::appendExtensionData to collect multiple values in the ParserOutput rather than destructively updating stored values. (T300981)
 * The signatures of the following methods from the ParserOutput class were narrowed, restricting the permitted argument types:
 * Access to the following public or protected properties of OutputPage was deprecated; they will be made private or removed in a future release. Use accessor functions instead.
 * The following methods were deprecated; use ::setPreventClickjacking(..) instead:
 * OutputPage::enableClientCache was deprecated, because it is universally used to do the opposite -- use OutputPage::disableClientCache instead.
 * Sanitizer::removeHTMLtags has been deprecated. Its output can include unbalanced or ill-formed HTML and thus external callers may be misled about how to safely incorporate its output into a page. It is recommended to use the new Sanitizer::removeSomeTags method instead, which will always return balanced HTML.
 * EventRelayerKafka was deprecated. To use $wgEventRelayerConfig with Kafka, add a similar class to your code.
 * MediaWiki\Logger\Monolog\KafkaHandler was deprecated. Consider using $wgMWLoggerDefaultSpi with SyslogHandler, or to use Kafka, add a similar Monolog handler class to your code.
 * Collation::singleton and ::factory now trigger deprecation warnings.
 * The following methods in MWNamespace, all deprecated since 1.34, now emit deprecation warnings:
 * Return values in the parameter $pageLang of the hook PageContentLanguage with other types than a Language object, deprecated since 1.33, now emits deprecation warnings.
 * Passing a db to BlockRestrictionStore::loadByBlockId is deprecated. BlockRestrictionStoreFactory should be used to fetch a correct BlockRestrictionStore instead.
 * All external access to ParserOutput and CacheTime classes properties will now emit deprecation warnings. Use getters and setters instead.
 * The custom jQuery event `watchpage.mw` emitted on #ca-watch and #ca-unwatch is now deprecated in favour of the new `wikipage.watchlistChange` hook.
 * The global function wfLogProfilingData has been deprecated without a replacement. The logic has been moved to the MediaWiki class.
 * The "trace" option of SectionProfiler has been deprecated.
 * The PageArchive class has had several methods deprecated. The replacements are as follows:
 * PageUpdater::isUnchanged has been deprecated, use wasRevisionCreated instead.
 * The `mediawiki.pager.tablePager` module was deprecated in favor of the more generic `mediawiki.pager.styles`.
 * wfGetCache and wfGetMainCache, both deprecated since 1.32, now emit deprecation warnings.
 * LinkCache::addGoodLinkObj has been hard deprecated.
 * ApiStashEdit::parseAndStash has been hard deprecated.
 * Content::prepareSave was hard-deprecated, now emits deprecation warnings. Use ContentHandler::validateSave instead.
 * The hooks LinksUpdateAfterInsert and LinksUpdateConstructed were deprecated.
 * Access to all public properties in LinksUpdate was deprecated.
 * The global variable $IP has been deprecated for use in application logic. It will remain available for use in LocalSettings.php for now, though $wgBaseDirectory is preferred. Application logic should use the BaseDirectory setting from the main config. Tests and framework code that need to function without MediaWiki being fully initialized should use the MW_INSTALL_PATH constant.
 * The global function wfWikiID, deprecated since 1.35, now emits deprecation warnings.
 * AbstractBlock::getBy now takes a wikiId as a parameter and emits deprecation warnings in case of cross-wiki accesses.
 * The `button` parameter for `bindUpdateAriaExpandedOnInput` and `updateAriaExpanded` in checkboxHack.js have been deprecated. `bindToggleOnSpaceEnter` has also been deprecated in favor of `bindToggleOnEnter`.
 * IDatabase::lockTables and IDatabase::unlockTables have been deprecated with no replacement. Instead, callers should batch updates into atomic transactions, using FOR UPDATE for SELECT queries.
 * EditPage::addNewLineAtEnd was deprecated; use TextboxBuilder::addNewLineAtEnd instead.
 * EditPage::getCopywarn was deprecated; use EditPage::getCopyrightWarning instead.
 * EditPage::getCopyrightWarning without passing a MessageLocalizer parameter has been deprecated.
 * Passing the $formCallback parameter to EditPage::showEditForm, deprecated in 1.25 and previously emitting a warn notice, now emits a deprecation notice.
 * EditPage::$action has been deprecated.
 * The following properties in EditPage now emit deprecation notices when used from another class:
 * The HTMLForm methods getPreText, setPreText, addPreText, getPostText, setPostText, addPostText, getHeaderText, setHeaderText, addHeaderText, getFooterText, setFooterText and addFooterText have been renamed to getPreHtml, setPreHtml, addPreHtml, getPostHtml, setPostHtml, addPostHtml, getHeaderHtml, setHeaderHtml, addHeaderHtml, getFooterHtml, setFooterHtml and addFooterHtml respectively.
 * The FormSpecialPage methods preText and postText have been renamed to preHtml and postHtml respectively.
 * Article::doDelete, deprecated in 1.37, now emits deprecation notices.
 * The following Less mediawiki.mixins have been deprecated:
 * Category::getPageCount now takes a parameter. Category::COUNT_ALL_MEMBERS return count of all members while Category::COUNT_CONTENT_PAGES return that of content pages. For the former behavior use Category::getMemberCount
 * Using `new HTMLForm( … )` or `HTMLForm::factory( … )` without the $context parameter is now deprecated.
 * BagOStuff::incr and BagOStuff::decr are now deprecated.
 * Action::exists and ActionFactory::actionExists are deprecated, use (bool)ActionFactory::getAction.

Other changes in 1.38
- The name and ID of the submit button are now `wpConfirmB`, not `mw-filedelete-submit` - The ID of the form is now `deleteconfirm`, not `mw-img-deleteconfirm` - The `mw-filedelete-editreasons` class was replaced with `mw-delete-editreasons` The goal of these changes is to make the HTML more similar to that of normal page deletion.
 * The following things were changed in the file deletion form:
 * ParserOptions created with ::newFrom* or ::newCanonical are now identical.
 * MediaWiki initialization order have been changed to load vendor autoload earlier. This means that extensions that are installed via composer and execute code upon autoloading can not depend on any MediaWiki classes, constants or globals in that code.
 * The source of truth for configuration defaults is now the MainConfigSchema class. DefaultSettings.php still exists for backwards compatibility. A PHP file generated for optimized loading will be used in Setup.php to initialize configuration variables. Setup.php can be made to load DefaultSettings.php as before by setting MW_USE_LEGACY_DEFAULT_SETTINGS as an environment variable (e.g. via SetEnv in htaccess) or a PHP constant (e.g. via auto_prepend_file in php.ini).

Compatibility
MediaWiki 1.38 requires PHP 7.3.19 or later and the following PHP extensions:


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

MySQL/MariaDB is the recommended DBMS. PostgreSQL or SQLite can also be used, but support for them is somewhat less mature.

The supported versions are:


 * MySQL 5.5.8 or later
 * PostgreSQL 9.4 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.