RELEASE-NOTES-1.27

   1 == MediaWiki 1.27 ==
   2
   3 THIS IS NOT A RELEASE YET
   4
   5 MediaWiki 1.27 is an alpha-quality branch and is not recommended for use in
   6 production.
   7
   8 === PHP version requirement ===
   9 As of 1.27, MediaWiki now requires PHP 5.5.9 or higher. This corresponds with
  10 HHVM 3.1.
  11
  12 === Configuration changes in 1.27 ===
  13 * $wgAllowMicrodataAttributes and $wgAllowRdfaAttributes were removed,
  14   now always enabled. If you use RDFa on your wiki, you now have to explicitly
  15   set $wgHtml5Version to 'HTML+RDFa 1.0' or 'XHTML+RDFa 1.0'.
  16 * $wgUseLinkNamespaceDBFields was removed.
  17 * Deprecated $wgResourceLoaderMinifierStatementsOnOwnLine and
  18   $wgResourceLoaderMinifierMaxLineLength, because there was little value in
  19   making the behavior configurable. The default values (`false` for the former,
  20   1000 for the latter) are now hard-coded.
  21 * $wgDebugDumpSqlLength was removed (deprecated in 1.24).
  22 * $wgDebugDBTransactions was removed (deprecated in 1.20).
  23 * $wgUseXVO has been removed, as it provides functionality only used by
  24   custom Wikimedia patches against Squid 2.x that probably noone uses in
  25   production anymore. There is now $wgUseKeyHeader that provides similar
  26   functionality but instead of the MediaWiki-specific X-Vary-Options header,
  27   uses the draft Key header standard.
  28 * $wgScriptExtension (and support for '.php5' entry points) was removed. See the
  29   deprecation notice in the release notes for version 1.25 for advice on how to
  30   preserve support for '.php5' entry points via URL rewriting.
  31 * Password handling via the User object has been deprecated and partially
  32   removed, pending the future introduction of AuthManager. In particular:
  33 ** expirePassword(), getPasswordExpireDate(), resetPasswordExpiration(), and
  34    getPasswordExpired() have been removed. They were unused outside of core.
  35 ** The mPassword, mNewpassword, mNewpassTime, and mPasswordExpires fields are
  36    now private and will be removed in the future.
  37 ** The getPassword() and getTemporaryPassword() methods now throw
  38    BadMethodCallException and will be removed in the future.
  39 ** The ability to pass 'password' and 'newpassword' to createNew() has been
  40    removed. The only users of it seem to have been using it to set invalid
  41    passwords, and so shouldn't be greatly affected.
  42 ** setPassword(), setInternalPassword(), and setNewpassword() have been
  43    deprecated, pending the introduction of AuthManager.
  44 ** User::randomPassword() is deprecated in favor of a new method
  45    PasswordFactory::generateRandomPasswordString()
  46 ** User::getPasswordFactory() is deprecated, callers should just create a
  47    PasswordFactory themselves.
  48 ** A new constructor, User::newSystemUser(), has been added to simplify the
  49    creation of passwordless "system" users for logged actions.
  50 * $wgMaxSquidPurgeTitles was removed.
  51 * $wgAjaxWatch was removed. This is now enabled by default.
  52 * $wgUseInstantCommons now hotlinks Commons images by default instead of
  53   downloading originals and thumbnailing them locally. This allows wikis to save
  54   on CPU and bandwidth while reducing time to first byte for pages, even without
  55   a thumbnail handler. See $wgForeignFileRepos documentation for tweaks.
  56 * (T27397) WebP is enabled by default as an uploadable filetype.
  57 * (T48998) $wgArticlePath must now be either a full url, or start with a "/".
  58 * $wgRateLimitLog was removed; use $wgDebugLogGroups['ratelimit'] instead.
  59 * Deprecated API formats dbg, txt, and yaml have been removed.
  60 * CLDRPluralRule* classes have been replaced with
  61   wikimedia/cldr-plural-rule-parser.
  62 * Removed $wgProfilePerHost, $wgUDPProfilerHost, $wgUDPProfilerPort,
  63   $wgUDPProfilerFormatString, $wgStatsMethod, $wgAggregateStatsID,
  64   $wgStatsFormatString, and $wgProfileCallTree (deprecated since 1.20).
  65 * For proper operation of LocalIdLookup with shared user tables, ensure that
  66   $wgSharedDB and $wgSharedTables are properly set even on the "central" wiki
  67   that all others are sharing from and that $wgLocalDatabases is set to the
  68   full list of sharing wikis on all those wikis.
  69 * Massive overhaul to session handling:
  70 ** $wgSessionsInObjectCache is no longer supported and must be true, due to
  71    MediaWiki\Session\SessionManager. $wgSessionHandler is similarly no longer
  72    used.
  73 ** ObjectCacheSessionHandler is removed, replaced with
  74    MediaWiki\Session\PhpSessionHandler.
  75 ** PHP session handling in general ($_SESSION, session_id(), and so on) is
  76    deprecated. Use MediaWiki\Session\SessionManager instead. A new config
  77    variable, $wgPHPSessionHandling, is available to cause use of $_SESSION to
  78    issue a deprecation warning or to cause most PHP session handling to throw
  79    exceptions.
  80 ** Deprecated UserSetCookies hook. Session-handling extensions should generally
  81    be creating a custom subclass of CookieSessionProvider. Other extensions
  82    messing with cookies can no longer count on user data being saved in cookies
  83    versus other methods.
  84 ** Deprecated UserLoadFromSession hook, extensions should create a
  85    MediaWiki\Session\SessionProvider.
  86 ** The User cannot be loaded from session until after Setup.php completes.
  87    Attempts to do so will be ignored and the User will remain unloaded.
  88 ** CSRF tokens may be fetched from the MediaWiki\Session\Session, which uses
  89    the MediaWiki\Session\Token class.
  90 * MediaWiki will now auto-create users as necessary, removing the need for
  91   extensions to do so. An 'autocreateaccount' right is added to allow
  92   auto-creation when 'createaccount' is not granted to all users.
  93 * Deprecated AuthPluginAutoCreate hook in favor of LocalUserCreated.
  94 * Most cookie-handling methods in User are deprecated.
  95 * $wgAllowAsyncCopyUploads and $CopyUploadAsyncTimeout were removed. This was an
  96   experimental feature that has never worked.
  97 * Login and createaccount tokens now vary by timestamp.
  98 * LoginForm::getLoginToken() and LoginForm::getCreateaccountToken()
  99   return a MediaWiki\Session\Token, and tokens must be checked using that
 100   class's methods.
 101 * $wgEnotifUseJobQ was removed and the job queue is always used.
 102 * The functionality of the ApiSandbox extension has been merged into core. The
 103   extension should no longer be used.
 104 * $wgPreloadJavaScriptMwUtil was removed (deprecated in 1.26).
 105   Extensions, skins, gadgets and scripts that use the mediawiki.util module must
 106   express a dependency on it.
 107 * $wgIncludeLegacyJavaScript, deprecated in MediaWiki 1.26, now defaults false.
 108   Extensions, skins, gadgets and scripts that need the mediawiki.legacy.wikibits
 109   module should express a dependency on it.
 110 * Removed configuration option $wgCopyrightIcon (deprecated since 1.18). Use
 111   $wgFooterIcons['copyright']['copyright'] instead.
 112 * ApiMain::getShowVersions() was removed (deprecated in 1.21).
 113 * ApiMain::addModule() was removed (deprecated in 1.21).
 114 * ApiMain::addFormat() was removed (deprecated in 1.21).
 115 * ApiMain::getFormats() was removed (deprecated in 1.21).
 116
 117 === New features in 1.27 ===
 118 * $wgDataCenterUpdateStickTTL was also added. This decides how long a user
 119   sticks to the primary DC (via cookies) after they make changes to the site.
 120 * Added a new hook, 'UserMailerTransformContent', to transform the contents
 121   of an email. This is similar to the EmailUser hook but applies to all mail
 122   sent via UserMailer.
 123 * Added a new hook, 'UserMailerTransformMessage', to transform the contents
 124   of an emai after MIME encoding.
 125 * Added a new hook, 'UserMailerSplitTo', to control which users have to be
 126   emailed separately (ie. there is a single address in the To: field) so
 127   user-specific changes to the email can be applied safely.
 128 * $wgCdnMaxageLagged was added, which limits the CDN cache TTL
 129   when any load balancer uses a DB that is lagged beyond the 'max lag'
 130   setting in the relevant section of $wgLBFactoryConf.
 131 * User::newSystemUser() may be used to simplify the creation of passwordless
 132   "system" users for logged actions from scripts and extensions.
 133 * Extensions can now return detailed error information via the API when
 134   preventing user actions using 'getUserPermissionsErrors' and similar hooks
 135   by using ApiMessage instances instead of strings for the $result value.
 136 * $wgAPIMaxLagThreshold was added to limit bot changes when databases lag
 137   becomes too high.
 138 * Skins and extensions can now use FlexBox mixins (.flex-display(@display: flex)
 139   and .flex(@grow: 1, @shrink: 1, @width: auto, @order: 1)) in Less to create
 140   cross-browser-compatible FlexBox rules. Users will still need to add fallback
 141   float rules or the like for compatibility with IE9- separately.
 142 * Added MWTimestamp::getTimezoneString() which returns the localized timezone
 143   string, if available. To localize this string, see the comments of
 144   $wgLocaltimezone in includes/DefaultSettings.php.
 145 * Added CentralIdLookup, a service that allows extensions needing a concept of
 146   "central" users to get that without having to know about specific central
 147   authentication extensions.
 148 * $wgMaxUserDBWriteDuration added to limit huge user-generated transactions.
 149   Regular web request transactions that takes longer than this are aborted.
 150 * Added a new hook, 'TitleMoveCompleting', which runs before a page move is
 151   committed.
 152 * $wgCdnReboundPurgeDelay was added to provide secondary delayed purges of URLs
 153   from CDN to mitigate DB replication lag and WAN cache purge lag.
 154 * (T49162) Installer will default to setting CACHE_ACCEL as the main cache type
 155   if it is available.
 156 * It is now possible to patrol file uploads (both for new files and new versions
 157   of existing files). Special:NewFiles has gained an option to filter by patrol
 158   status. This functionality can be disabled using $wgUseFilePatrol.
 159 * MediaWiki\Session infrastructure allows for easier use of session mechanisms
 160   other than the usual cookies.
 161 ** SessionMetadata and SessionCheckInfo hooks allow for setting and checking
 162    custom session metadata.
 163 * Added MWGrants and associated configuration settings $wgGrantPermissions and
 164   $wgGrantPermissionGroups to hold configuration for authentication features
 165   such as OAuth that want to allow restricting the user rights a user may make
 166   use of.
 167 ** If you're already using the OAuth extension, these new variables are
 168    identical to (and will replace) $wgMWOAuthGrantPermissions and
 169    $wgMWOAuthGrantPermissionGroups.
 170 * Added MWRestrictions as a class to check restrictions on a WebRequest, e.g.
 171   to assert that the request comes from a particular IP range.
 172 * Added bot passwords, a rights-restricted login mechanism for API-using bots.
 173 * Whitelisted the following HTML attributes for all elements in wikitext:
 174   aria-describedby, aria-flowto, aria-label, aria-labelledby, aria-owns.
 175 * Removed "presentation" restriction on the HTML role attribute in wikitext.
 176   All values are now allowed for the role attribute.
 177 * $wgContentHandlers now also supports callbacks to create an instance of the
 178   appropriate ContentHandler subclass.
 179 * Added $wgAuthenticationTokenVersion, which if non-null prevents the
 180   user_token database field from being exposed in cookies. Setting this would
 181   be a good idea, but will log out all current sessions.
 182 * $wgEventRelayerConfig was added, for managing PubSub event relay configuration,
 183   specifically for reliable CDN url purges.
 184 * Requests have unique IDs, equal to the UNIQUE_ID environment variable (when
 185   MediaWiki is behind Apache+mod_unique_id or something similar) or a randomly-
 186   generated 24-character string. This request ID is used to annotate log records
 187   and error messages. It is available client-side via mw.config.get( 'wgRequestId' ).
 188   The request ID supplants exception IDs. Accordingly, MWExceptionHandler::getLogId()
 189   is deprecated.
 190
 191 === External library changes in 1.27 ===
 192
 193 ==== Upgraded external libraries ====
 194 * Updated oojs/oojs-ui from v0.12.12 to v0.13.3.
 195 * Updated composer/semver from v1.0.0 to v1.2.0.
 196 * Updated liuggio/statsd-php-client to 1.0.18.
 197 * Updated QUnit from v1.18.0 to v1.22.0.
 198
 199 ==== New external libraries ====
 200 * Added wikimedia/base-convert v1.0.1.
 201 * Added wikimedia/cldr-plural-rule-parser v1.0.0.
 202 * Added wikimedia/relpath v1.0.3.
 203 * Added wikimedia/running-stat v1.1.0.
 204 * Added wikimedia/php-session-serializer v1.0.3.
 205
 206 ==== Removed and replaced external libraries ====
 207
 208 === Bug fixes in 1.27 ===
 209 * Special:Upload will now display correct maximum allowed file size when running
 210   under HHVM (T116347).
 211
 212 === Action API changes in 1.27 ===
 213 * Added list=allrevisions.
 214 * generator=recentchanges now has the option to generate revids.
 215 * ApiPageSet::setRedirectMergePolicy() was added. This allows generator
 216   modules to define how generator data for a redirect source gets merged
 217   into the redirect destination.
 218 * prop=imageinfo&iiprop=uploadwarning will no longer include the possibility of
 219   "was-deleted" warning.
 220 * Added difftotextpst to query=revisions which preforms a pre-save transform on
 221   the text before diffing it.
 222 * Deprecated formats dbg, txt, and yaml have been removed.
 223 * (T47988) The protect log event details now use new-style formatting.
 224 * The following response properties from action=login are deprecated, and may
 225   be removed in the future: lgtoken, cookieprefix, sessionid. Clients should
 226   handle cookies to properly manage session state.
 227 * action=login transparently allows login using bot passwords. Clients should
 228   merely need to change the username and password used after setting up a bot
 229   password.
 230 * action=upload no longer understands statuskey, asyncdownload or leavemessage.
 231
 232 === Action API internal changes in 1.27 ===
 233 * ApiQueryORM removed.
 234 * The following classes have been removed:
 235 ** ApiFormatDbg
 236 ** ApiFormatTxt
 237 ** ApiFormatYaml
 238 * ApiBase::addTokenProperties() was removed (deprecated since 1.24).
 239 * ApiBase::getFinalPossibleErrors() was removed (deprecated since 1.24).
 240 * ApiBase::getFinalResultProperties() was removed (deprecated since 1.24).
 241 * ApiBase::getRequireAtLeastOneParameterErrorMessages() was removed (deprecated since 1.24).
 242 * ApiBase::getPossibleErrors() was removed (deprecated since 1.24).
 243 * ApiBase::getRequireMaxOneParameterErrorMessages() was removed (deprecated since 1.24).
 244 * ApiBase::getRequireOnlyOneParameterErrorMessages() was removed (deprecated since 1.24).
 245 * ApiBase::getResultProperties() was removed (deprecated since 1.24).
 246 * ApiBase::getTitleOrPageIdErrorMessage() was removed (deprecated since 1.24).
 247 * ApiBase::parseErrors() was removed (deprecated since 1.24).
 248 * ApiQueryBase::titleToKey(), ApiQueryBase::keyToTitle() and
 249   ApiQueryBase::keyPartToTitle() all removed (deprecated since 1.24).
 250 * ApiQueryBase::checkRowCount() was removed (deprecated since 1.24).
 251 * ApiQueryBase::getDirectionDescription() was removed (deprecated since 1.25).
 252 * ApiQuery::getGenerators() was removed (deprecated since 1.21).
 253 * ApiQuery::getModules() was removed (deprecated since 1.21).
 254 * ApiQuery::getModuleType() was removed (deprecated since 1.21).
 255 * ApiQuery::setGeneratorContinue() was removed (deprecated since 1.24).
 256 * ApiMain::getModules() was removed (deprecated since 1.21).
 257 * ApiBase::getVersion() was removed (deprecated since 1.21).
 258 * Language::getLangObj() was removed (deprecated since 1.24).
 259 * Language::getLanguageName() was removed (deprecated since 1.20).
 260 * Language::getLanguageNames() was removed (deprecated since 1.20).
 261 * Language::getTranslatedLanguageNames() was removed (deprecated since 1.20).
 262 * Language::specialPage() was removed (deprecated since 1.24).
 263 * MediaWikiTestCase::assertException() was removed (deprecated since 1.22).
 264 * OutputPage::getHeadItems() was removed (deprecated since 1.24).
 265 * OutputPage::getScript() was removed (deprecated since 1.24).
 266 * OutputPage::out() was removed (deprecated since 1.22).
 267 * OutputPage::setAllowedModules() was removed (deprecated since 1.24).
 268 * UserrightsPage::makeGroupNameListForLog() was removed (deprecated since 1.21).
 269
 270 === Languages updated in 1.27 ===
 271
 272 MediaWiki supports over 350 languages. Many localisations are updated
 273 regularly. Below only new and removed languages are listed, as well as
 274 changes to languages because of Phabricator reports.
 275
 276 * (T113688) Change default numerals from Gurmukhi to Arabic for Punjabi locale.
 277
 278 === Other changes in 1.27 ===
 279 * ProfilerOutputUdp was removed. Note that there is a ProfilerOutputStats class.
 280 * WikiPage::doDeleteArticleReal() and WikiPage::doDeleteArticle() now
 281   ignore the 2nd and 3rd arguments (formerly $id and $commit).
 282 * Removed "loaderScripts" option from ResourceLoaderFileModule class.
 283 * Removed ORM-like wrapper added in 1.20.
 284 * LinkCache::getGoodLinks and LinkCache::getBadLinks were removed
 285   (deprecated in 1.26).
 286 * WikiPage::doQuickEdit() was removed (deprecated since 1.21).
 287 * Removed SiteObject and SiteArray classes (deprecated in 1.21).
 288 * MessageBlobStore::getInstance() was removed (deprecated since 1.25).
 289 * (T84937) Free external links ("autolinked" urls) will now be terminated
 290   by &nbsp; and HTML entity encodings of &nbsp, <, and >.
 291 * (T36948) The default file revert message's timestamp is now in
 292   $wgLocaltimezone, instead of UTC.
 293 * The default name of the 'suppress' group page has been changed from
 294   'Project:Oversight' to 'Project:Suppress'.
 295 * DatabaseBase::resultObject() is now protected (use outside Database classes
 296   not necessary since 1.11).
 297 * Calling ResourceLoaderFileModule::readStyleFiles() without a
 298   ResourceLoaderContext instance is deprecated.
 299 * ResourceLoader::getLessCompiler() now takes an optional parameter of
 300   additional LESS variables to set for the compiler.
 301 * wfBaseConvert() marked as deprecated, use Wikimedia\base_convert() directly
 302   instead.
 303 * Obsolete maintenance scripts clearCacheStats.php and showCacheStats.php
 304   were removed. The underlying data is sent to StatsD (see $wgStatsdServer).
 305 * Removed msg_resource_links database table and associated code.
 306 * Removed msg_resource database table and associated code.
 307 * Skin::getNamespaceNotice() was removed.
 308 * wfIsConfiguredProxy() was removed (deprecated since 1.24).
 309 * wfDebugTimer() was removed (deprecated since 1.25).
 310 * wfIsTrustedProxy() was removed (deprecated since 1.24).
 311 * wfGetIP() was removed (deprecated since 1.19).
 312 * MWHookException was removed.
 313 * OutputPage::appendSubtitle() was removed (deprecated since 1.19).
 314 * OutputPage::loginToUse() was removed (deprecated since 1.19).
 315 * Article::loadContent() was removed (deprecated since 1.19).
 316 * User::editToken() was removed (deprecated since 1.19).
 317 * Removed --force-normal option of dumpBackup.php, as it no longer served
 318   any useful purpose since 1.22.
 319 * The functions processOption() and processArgs() on the BackupDumper and
 320   TextPassDumper classes have been removed.
 321 * The maintenance/backupTextPass.inc file was deleted. You should include
 322   maintenance/dumpTextPass.php instead.
 323 * WikiPage::getUsedTemplates() was removed (deprecated since 1.19).
 324 * wfEmptyMsg() was removed (deprecated since 1.18).
 325 * OutputPage::permissionRequired() was removed (deprecated since 1.18).
 326 * OutputPage::blockedPage() was removed (deprecated since 1.18).
 327 * User::getSkin() was removed (deprecated since 1.18).
 328 * OutputPage::includeJQuery() was removed (deprecated since 1.17).
 329 * WikiPage::updateRestrictions() was removed (deprecated since 1.19).
 330 * WikiPage::testPreSaveTransform() was removed (deprecated since 1.19).
 331 * LogPage::logName() was removed (deprecated since 1.19).
 332 * LogPage::logHeader() was removed (deprecated since 1.19).
 333 * wfCheckLimits() was removed (deprecated since 1.24).
 334 * Linker::makeKnownLinkObj() was removed (deprecated since 1.16).
 335 * Linker::makeLinkObj() was removed (deprecated since 1.16).
 336 * wfMsgForContentNoTrans() was removed (deprecated since 1.18).
 337 * ChangesList::usePatrol was removed (deprecated since 1.22).
 338 * wfMsgNoTrans() was removed (deprecated since 1.18).
 339 * Linker::makeImageLink2 was removed (deprecated since 1.20).
 340 * Title::userIsWatching() was removed (deprecated since 1.20).
 341 * Removed WaitForSlave maintenance script; use SELECT MASTER_POS_WAIT()
 342   database function directly instead.
 343 * wfMsg() was removed (deprecated since 1.18).
 344 * wfMsgForContent() was removed (deprecated since 1.18).
 345 * wfMsgReal() was removed (deprecated since 1.18).
 346 * wfMsgGetKey() was removed (deprecated since 1.18).
 347 * wfMsgHtml() was removed (deprecated since 1.18).
 348 * wfMsgWikiHtml() was removed (deprecated since 1.18).
 349 * wfMsgExt() was removed (deprecated since 1.18).
 350 * Language::armourMath() was removed (deprecated since 1.22).
 351 * LanguageConverter::armourMath() was removed (deprecated since 1.22).
 352 * FakeConverter::armourMath() was removed (deprecated since 1.22).
 353 * The unused jquery.validate ResourceLoader module was removed.
 354 * FileRepo::getRootUrl() was removed (deprecated since 1.20).
 355 * User::generateToken() was removed (deprecated since 1.20).
 356 * WikiPage::getRawText() was removed (deprecated since 1.21).
 357 * ParserOutput::hasCustomDataUpdates() was removed (deprecated since 1.25).
 358 * ParserOutput::addSecondaryDataUpdate() was removed (deprecated since 1.25).
 359 * ParserOutput::getSecondaryDataUpdates() was removed (deprecated since 1.25).
 360 * Gallery images with multiple caption pipes no longer concatenate them all
 361   together but instead pick the final one, similar to image syntax.
 362 * XML-like parser tags (such as <gallery>), when unclosed, will be left unparsed
 363   rather than consume everything until the end of the page.
 364 * New maintenance script resetUserEmail.php allows sysadmins to reset user emails in case
 365   a user forgot password/account was stolen.
 366 * wfCheckEntropy() was removed (deprecated in 1.27).
 367 * Browser support for Internet Explorer 8 lowered from Grade A to Grade C.
 368 * ContentHandler::supportsCategories method added. Default is true.
 369   CategoryMembershipChangeJob updates are skipped for content that
 370   does not support categories.
 371 * wikidiff difference engine is no longer supported, anyone still using it are encouraged
 372   to upgrade to wikidiff2 which is actively maintained and has better package availability.
 373 * Database logic was removed from WatchedItem and a WatchedItemStore was created:
 374 ** WatchedItem::IGNORE_USER_RIGHTS and WatchedItem::CHECK_USER_RIGHTS were deprecated.
 375    User::IGNORE_USER_RIGHTS and User::CHECK_USER_RIGHTS were introduced.
 376 ** WatchedItem::fromUserTitle was deprecated in favour of the constructor.
 377 ** WatchedItem::resetNotificationTimestamp was deprecated.
 378 ** WatchedItem::batchAddWatch was deprecated.
 379 ** WatchedItem::addWatch was deprecated.
 380 ** WatchedItem::removeWatch was deprecated.
 381 ** WatchedItem::isWatched was deprecated.
 382 ** WatchedItem::duplicateEntries was deprecated.
 383 ** EmailNotification::updateWatchlistTimestamp was deprecated.
 384 ** User::getWatchedItem was removed.
 385 * Unit tests don't work with external PHPUnit anymore, Composer is now the only supported
 386   way. Run `composer install` to install it and other dev dependencies to run unit tests.
 387 * wl_id field added to the watchlist table.
 388 * Revision::getRawText() was removed (deprecated since 1.21).
 389
 390 == Compatibility ==
 391
 392 MediaWiki 1.27 requires PHP 5.5.9 or later. There is experimental support for
 393 HHVM 3.6.5 or later.
 394
 395 MySQL is the recommended DBMS. PostgreSQL or SQLite can also be used, but
 396 support for them is somewhat less mature. There is experimental support for
 397 Oracle and Microsoft SQL Server.
 398
 399 The supported versions are:
 400
 401 * MySQL 5.0.3 or later
 402 * PostgreSQL 8.3 or later
 403 * SQLite 3.3.7 or later
 404 * Oracle 9.0.1 or later
 405 * Microsoft SQL Server 2005 (9.00.1399)
 406
 407 == Upgrading ==
 408
 409 1.27 has several database changes since 1.26, and will not work without schema
 410 updates. Note that due to changes to some very large tables like the revision
 411 table, the schema update may take quite long (minutes on a medium sized site,
 412 many hours on a large site).
 413
 414 If upgrading from before 1.11, and you are using a wiki as a commons
 415 repository, make sure that it is updated as well. Otherwise, errors may arise
 416 due to database schema changes.
 417
 418 If upgrading from before 1.7, you may want to run refreshLinks.php to ensure
 419 new database fields are filled with data.
 420
 421 If you are upgrading from MediaWiki 1.4.x or earlier, you should upgrade to
 422 1.5 first. The upgrade script maintenance/upgrade1_5.php has been removed
 423 with MediaWiki 1.21.
 424
 425 Don't forget to always back up your database before upgrading!
 426
 427 See the file UPGRADE for more detailed upgrade instructions.
 428
 429 For notes on 1.26.x and older releases, see HISTORY.
 430
 431 == Online documentation ==
 432
 433 Documentation for both end-users and site administrators is available on
 434 MediaWiki.org, and is covered under the GNU Free Documentation License (except
 435 for pages that explicitly state that their contents are in the public domain):
 436
 437        https://www.mediawiki.org/wiki/Documentation
 438
 439 == Mailing list ==
 440
 441 A mailing list is available for MediaWiki user support and discussion:
 442
 443        https://lists.wikimedia.org/mailman/listinfo/mediawiki-l
 444
 445 A low-traffic announcements-only list is also available:
 446
 447        https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce
 448
 449 It's highly recommended that you sign up for one of these lists if you're
 450 going to run a public MediaWiki, so you can be notified of security fixes.
 451
 452 == IRC help ==
 453
 454 There's usually someone online in #mediawiki on irc.freenode.net.