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
 111 === New features in 1.27 ===
 112 * $wgDataCenterUpdateStickTTL was also added. This decides how long a user
 113   sticks to the primary DC (via cookies) after they make changes to the site.
 114 * Added a new hook, 'UserMailerTransformContent', to transform the contents
 115   of an email. This is similar to the EmailUser hook but applies to all mail
 116   sent via UserMailer.
 117 * Added a new hook, 'UserMailerTransformMessage', to transform the contents
 118   of an emai after MIME encoding.
 119 * Added a new hook, 'UserMailerSplitTo', to control which users have to be
 120   emailed separately (ie. there is a single address in the To: field) so
 121   user-specific changes to the email can be applied safely.
 122 * $wgCdnMaxageLagged was added, which limits the CDN cache TTL
 123   when any load balancer uses a DB that is lagged beyond the 'max lag'
 124   setting in the relevant section of $wgLBFactoryConf.
 125 * User::newSystemUser() may be used to simplify the creation of passwordless
 126   "system" users for logged actions from scripts and extensions.
 127 * Extensions can now return detailed error information via the API when
 128   preventing user actions using 'getUserPermissionsErrors' and similar hooks
 129   by using ApiMessage instances instead of strings for the $result value.
 130 * $wgAPIMaxLagThreshold was added to limit bot changes when databases lag
 131   becomes too high.
 132 * Skins and extensions can now use FlexBox mixins (.flex-display(@display: flex)
 133   and .flex(@grow: 1, @shrink: 1, @width: auto, @order: 1)) in Less to create
 134   cross-browser-compatible FlexBox rules. Users will still need to add fallback
 135   float rules or the like for compatibility with IE9- separately.
 136 * Added MWTimestamp::getTimezoneString() which returns the localized timezone
 137   string, if available. To localize this string, see the comments of
 138   $wgLocaltimezone in includes/DefaultSettings.php.
 139 * Added CentralIdLookup, a service that allows extensions needing a concept of
 140   "central" users to get that without having to know about specific central
 141   authentication extensions.
 142 * $wgMaxUserDBWriteDuration added to limit huge user-generated transactions.
 143   Regular web request transactions that takes longer than this are aborted.
 144 * Added a new hook, 'TitleMoveCompleting', which runs before a page move is
 145   committed.
 146 * $wgCdnReboundPurgeDelay was added to provide secondary delayed purges of URLs
 147   from CDN to mitigate DB replication lag and WAN cache purge lag.
 148 * (T49162) Installer will default to setting CACHE_ACCEL as the main cache type
 149   if it is available.
 150 * It is now possible to patrol file uploads (both for new files and new versions
 151   of existing files). Special:NewFiles has gained an option to filter by patrol
 152   status. This functionality can be disabled using $wgUseFilePatrol.
 153 * MediaWiki\Session infrastructure allows for easier use of session mechanisms
 154   other than the usual cookies.
 155 ** SessionMetadata and SessionCheckInfo hooks allow for setting and checking
 156    custom session metadata.
 157 * Added MWGrants and associated configuration settings $wgGrantPermissions and
 158   $wgGrantPermissionGroups to hold configuration for authentication features
 159   such as OAuth that want to allow restricting the user rights a user may make
 160   use of.
 161 ** If you're already using the OAuth extension, these new variables are
 162    identical to (and will replace) $wgMWOAuthGrantPermissions and
 163    $wgMWOAuthGrantPermissionGroups.
 164 * Added MWRestrictions as a class to check restrictions on a WebRequest, e.g.
 165   to assert that the request comes from a particular IP range.
 166 * Added bot passwords, a rights-restricted login mechanism for API-using bots.
 167 * Whitelisted the following HTML attributes for all elements in wikitext:
 168   aria-describedby, aria-flowto, aria-label, aria-labelledby, aria-owns.
 169 * Removed "presentation" restriction on the HTML role attribute in wikitext.
 170   All values are now allowed for the role attribute.
 171 * $wgContentHandlers now also supports callbacks to create an instance of the
 172   appropriate ContentHandler subclass.
 173 * Added $wgAuthenticationTokenVersion, which if non-null prevents the
 174   user_token database field from being exposed in cookies. Setting this would
 175   be a good idea, but will log out all current sessions.
 176 * $wgEventRelayerConfig was added, for managing PubSub event relay configuration,
 177   specifically for reliable CDN url purges.
 178
 179 === External library changes in 1.27 ===
 180
 181 ==== Upgraded external libraries ====
 182 * Updated oojs/oojs-ui from v0.12.12 to v0.13.3.
 183 * Updated composer/semver from v1.0.0 to v1.2.0.
 184 * Updated liuggio/statsd-php-client to 1.0.18.
 185 * Updated QUnit from v1.18.0 to v1.22.0.
 186
 187 ==== New external libraries ====
 188 * Added wikimedia/base-convert v1.0.1.
 189 * Added wikimedia/cldr-plural-rule-parser v1.0.0.
 190 * Added wikimedia/relpath v1.0.3.
 191 * Added wikimedia/running-stat v1.1.0.
 192 * Added wikimedia/php-session-serializer v1.0.3.
 193
 194 ==== Removed and replaced external libraries ====
 195
 196 === Bug fixes in 1.27 ===
 197 * Special:Upload will now display correct maximum allowed file size when running
 198   under HHVM (T116347).
 199
 200 === Action API changes in 1.27 ===
 201 * Added list=allrevisions.
 202 * generator=recentchanges now has the option to generate revids.
 203 * ApiPageSet::setRedirectMergePolicy() was added. This allows generator
 204   modules to define how generator data for a redirect source gets merged
 205   into the redirect destination.
 206 * prop=imageinfo&iiprop=uploadwarning will no longer include the possibility of
 207   "was-deleted" warning.
 208 * Added difftotextpst to query=revisions which preforms a pre-save transform on
 209   the text before diffing it.
 210 * Deprecated formats dbg, txt, and yaml have been removed.
 211 * (T47988) The protect log event details now use new-style formatting.
 212 * The following response properties from action=login are deprecated, and may
 213   be removed in the future: lgtoken, cookieprefix, sessionid. Clients should
 214   handle cookies to properly manage session state.
 215 * action=login transparently allows login using bot passwords. Clients should
 216   merely need to change the username and password used after setting up a bot
 217   password.
 218 * action=upload no longer understands statuskey, asyncdownload or leavemessage.
 219
 220 === Action API internal changes in 1.27 ===
 221 * ApiQueryORM removed.
 222 * The following classes have been removed:
 223 ** ApiFormatDbg
 224 ** ApiFormatTxt
 225 ** ApiFormatYaml
 226 * ApiBase::addTokenProperties() was removed (deprecated since 1.24).
 227 * ApiBase::getFinalPossibleErrors() was removed (deprecated since 1.24).
 228 * ApiBase::getFinalResultProperties() was removed (deprecated since 1.24).
 229 * ApiBase::getRequireAtLeastOneParameterErrorMessages() was removed (deprecated since 1.24).
 230 * ApiBase::getPossibleErrors() was removed (deprecated since 1.24).
 231 * ApiBase::getRequireMaxOneParameterErrorMessages() was removed (deprecated since 1.24).
 232 * ApiBase::getRequireOnlyOneParameterErrorMessages() was removed (deprecated since 1.24).
 233 * ApiBase::getResultProperties() was removed (deprecated since 1.24).
 234 * ApiBase::getTitleOrPageIdErrorMessage() was removed (deprecated since 1.24).
 235 * ApiBase::parseErrors() was removed (deprecated since 1.24).
 236 * ApiQueryBase::titleToKey(), ApiQueryBase::keyToTitle() and
 237   ApiQueryBase::keyPartToTitle() all removed (deprecated since 1.24).
 238 * ApiQueryBase::checkRowCount() was removed (deprecated since 1.24).
 239 * ApiQueryBase::getDirectionDescription() was removed (deprecated since 1.25).
 240 * ApiQuery::getGenerators() was removed (deprecated since 1.21).
 241 * ApiQuery::getModules() was removed (deprecated since 1.21).
 242 * ApiQuery::getModuleType() was removed (deprecated since 1.21).
 243 * ApiQuery::setGeneratorContinue() was removed (deprecated since 1.24).
 244 * ApiMain::getModules() was removed (deprecated since 1.21).
 245 * ApiBase::getVersion() was removed (deprecated since 1.21).
 246 * Language::getLangObj() was removed (deprecated since 1.24).
 247 * Language::getLanguageName() was removed (deprecated since 1.20).
 248 * Language::getLanguageNames() was removed (deprecated since 1.20).
 249 * Language::getTranslatedLanguageNames() was removed (deprecated since 1.20).
 250 * Language::specialPage() was removed (deprecated since 1.24).
 251 * MediaWikiTestCase::assertException() was removed (deprecated since 1.22).
 252 * OutputPage::getHeadItems() was removed (deprecated since 1.24).
 253 * OutputPage::getScript() was removed (deprecated since 1.24).
 254 * OutputPage::out() was removed (deprecated since 1.22).
 255 * OutputPage::setAllowedModules() was removed (deprecated since 1.24).
 256
 257 === Languages updated in 1.27 ===
 258
 259 MediaWiki supports over 350 languages. Many localisations are updated
 260 regularly. Below only new and removed languages are listed, as well as
 261 changes to languages because of Phabricator reports.
 262
 263 * (T113688) Change default numerals from Gurmukhi to Arabic for Punjabi locale.
 264
 265 === Other changes in 1.27 ===
 266 * ProfilerOutputUdp was removed. Note that there is a ProfilerOutputStats class.
 267 * WikiPage::doDeleteArticleReal() and WikiPage::doDeleteArticle() now
 268   ignore the 2nd and 3rd arguments (formerly $id and $commit).
 269 * Removed "loaderScripts" option from ResourceLoaderFileModule class.
 270 * Removed ORM-like wrapper added in 1.20.
 271 * LinkCache::getGoodLinks and LinkCache::getBadLinks were removed
 272   (deprecated in 1.26).
 273 * WikiPage::doQuickEdit() was removed (deprecated since 1.21).
 274 * Removed SiteObject and SiteArray classes (deprecated in 1.21).
 275 * MessageBlobStore::getInstance() was removed (deprecated since 1.25).
 276 * (T84937) Free external links ("autolinked" urls) will now be terminated
 277   by &nbsp; and HTML entity encodings of &nbsp, <, and >.
 278 * (T36948) The default file revert message's timestamp is now in
 279   $wgLocaltimezone, instead of UTC.
 280 * The default name of the 'suppress' group page has been changed from
 281   'Project:Oversight' to 'Project:Suppress'.
 282 * DatabaseBase::resultObject() is now protected (use outside Database classes
 283   not necessary since 1.11).
 284 * Calling ResourceLoaderFileModule::readStyleFiles() without a
 285   ResourceLoaderContext instance is deprecated.
 286 * ResourceLoader::getLessCompiler() now takes an optional parameter of
 287   additional LESS variables to set for the compiler.
 288 * wfBaseConvert() marked as deprecated, use Wikimedia\base_convert() directly
 289   instead.
 290 * Obsolete maintenance scripts clearCacheStats.php and showCacheStats.php
 291   were removed. The underlying data is sent to StatsD (see $wgStatsdServer).
 292 * Removed msg_resource_links database table and associated code.
 293 * Removed msg_resource database table and associated code.
 294 * Skin::getNamespaceNotice() was removed.
 295 * wfIsConfiguredProxy() was removed (deprecated since 1.24).
 296 * wfDebugTimer() was removed (deprecated since 1.25).
 297 * wfIsTrustedProxy() was removed (deprecated since 1.24).
 298 * wfGetIP() was removed (deprecated since 1.19).
 299 * MWHookException was removed.
 300 * OutputPage::appendSubtitle() was removed (deprecated since 1.19).
 301 * OutputPage::loginToUse() was removed (deprecated since 1.19).
 302 * Article::loadContent() was removed (deprecated since 1.19).
 303 * User::editToken() was removed (deprecated since 1.19).
 304 * Removed --force-normal option of dumpBackup.php, as it no longer served
 305   any useful purpose since 1.22.
 306 * The functions processOption() and processArgs() on the BackupDumper and
 307   TextPassDumper classes have been removed.
 308 * The maintenance/backupTextPass.inc file was deleted. You should include
 309   maintenance/dumpTextPass.php instead.
 310 * WikiPage::getUsedTemplates() was removed (deprecated since 1.19).
 311 * wfEmptyMsg() was removed (deprecated since 1.18).
 312 * OutputPage::permissionRequired() was removed (deprecated since 1.18).
 313 * OutputPage::blockedPage() was removed (deprecated since 1.18).
 314 * User::getSkin() was removed (deprecated since 1.18).
 315 * OutputPage::includeJQuery() was removed (deprecated since 1.17).
 316 * WikiPage::updateRestrictions() was removed (deprecated since 1.19).
 317 * WikiPage::testPreSaveTransform() was removed (deprecated since 1.19).
 318 * LogPage::logName() was removed (deprecated since 1.19).
 319 * LogPage::logHeader() was removed (deprecated since 1.19).
 320 * wfCheckLimits() was removed (deprecated since 1.24).
 321 * Linker::makeKnownLinkObj() was removed (deprecated since 1.16).
 322 * Linker::makeLinkObj() was removed (deprecated since 1.16).
 323 * wfMsgForContentNoTrans() was removed (deprecated since 1.18).
 324 * ChangesList::usePatrol was removed (deprecated since 1.22).
 325 * wfMsgNoTrans() was removed (deprecated since 1.18).
 326 * Linker::makeImageLink2 was removed (deprecated since 1.20).
 327 * Title::userIsWatching() was removed (deprecated since 1.20).
 328 * Removed WaitForSlave maintenance script; use SELECT MASTER_POS_WAIT()
 329   database function directly instead.
 330 * wfMsg() was removed (deprecated since 1.18).
 331 * wfMsgForContent() was removed (deprecated since 1.18).
 332 * wfMsgReal() was removed (deprecated since 1.18).
 333 * wfMsgGetKey() was removed (deprecated since 1.18).
 334 * wfMsgHtml() was removed (deprecated since 1.18).
 335 * wfMsgWikiHtml() was removed (deprecated since 1.18).
 336 * wfMsgExt() was removed (deprecated since 1.18).
 337 * Language::armourMath() was removed (deprecated since 1.22).
 338 * LanguageConverter::armourMath() was removed (deprecated since 1.22).
 339 * FakeConverter::armourMath() was removed (deprecated since 1.22).
 340 * The unused jquery.validate ResourceLoader module was removed.
 341 * FileRepo::getRootUrl() was removed (deprecated since 1.20).
 342 * User::generateToken() was removed (deprecated since 1.20).
 343 * WikiPage::getRawText() was removed (deprecated since 1.21).
 344 * ParserOutput::hasCustomDataUpdates() was removed (deprecated since 1.25).
 345 * ParserOutput::addSecondaryDataUpdate() was removed (deprecated since 1.25).
 346 * ParserOutput::getSecondaryDataUpdates() was removed (deprecated since 1.25).
 347 * Gallery images with multiple caption pipes no longer concatenate them all
 348   together but instead pick the final one, similar to image syntax.
 349 * XML-like parser tags (such as <gallery>), when unclosed, will be left unparsed
 350   rather than consume everything until the end of the page.
 351 * New maintenance script resetUserEmail.php allows sysadmins to reset user emails in case
 352   a user forgot password/account was stolen.
 353 * wfCheckEntropy() was removed (deprecated in 1.27).
 354 * Browser support for Internet Explorer 8 lowered from Grade A to Grade C.
 355 * ContentHandler::supportsCategories method added. Default is true.
 356   CategoryMembershipChangeJob updates are skipped for content that
 357   does not support categories.
 358 * wikidiff difference engine is no longer supported, anyone still using it are encouraged
 359   to upgrade to wikidiff2 which is actively maintained and has better package availability.
 360 * Database logic was removed from WatchedItem and a WatchedItemStore was created:
 361 ** WatchedItem::IGNORE_USER_RIGHTS and WatchedItem::CHECK_USER_RIGHTS were deprecated.
 362    User::IGNORE_USER_RIGHTS and User::CHECK_USER_RIGHTS were introduced.
 363 ** WatchedItem::fromUserTitle was deprecated in favour of the constructor.
 364 ** WatchedItem::resetNotificationTimestamp was deprecated.
 365 ** WatchedItem::batchAddWatch was deprecated.
 366 ** WatchedItem::addWatch was deprecated.
 367 ** WatchedItem::removeWatch was deprecated.
 368 ** WatchedItem::isWatched was deprecated.
 369 ** WatchedItem::duplicateEntries was deprecated.
 370 ** EmailNotification::updateWatchlistTimestamp was deprecated.
 371 ** User::getWatchedItem was removed.
 372 * Unit tests don't work with external PHPUnit anymore, Composer is now the only supported
 373   way. Run `composer install` to install it and other dev dependencies to run unit tests.
 374 * wl_id field added to the watchlist table.
 375
 376 == Compatibility ==
 377
 378 MediaWiki 1.27 requires PHP 5.5.9 or later. There is experimental support for
 379 HHVM 3.6.5 or later.
 380
 381 MySQL is the recommended DBMS. PostgreSQL or SQLite can also be used, but
 382 support for them is somewhat less mature. There is experimental support for
 383 Oracle and Microsoft SQL Server.
 384
 385 The supported versions are:
 386
 387 * MySQL 5.0.3 or later
 388 * PostgreSQL 8.3 or later
 389 * SQLite 3.3.7 or later
 390 * Oracle 9.0.1 or later
 391 * Microsoft SQL Server 2005 (9.00.1399)
 392
 393 == Upgrading ==
 394
 395 1.27 has several database changes since 1.26, and will not work without schema
 396 updates. Note that due to changes to some very large tables like the revision
 397 table, the schema update may take quite long (minutes on a medium sized site,
 398 many hours on a large site).
 399
 400 If upgrading from before 1.11, and you are using a wiki as a commons
 401 repository, make sure that it is updated as well. Otherwise, errors may arise
 402 due to database schema changes.
 403
 404 If upgrading from before 1.7, you may want to run refreshLinks.php to ensure
 405 new database fields are filled with data.
 406
 407 If you are upgrading from MediaWiki 1.4.x or earlier, you should upgrade to
 408 1.5 first. The upgrade script maintenance/upgrade1_5.php has been removed
 409 with MediaWiki 1.21.
 410
 411 Don't forget to always back up your database before upgrading!
 412
 413 See the file UPGRADE for more detailed upgrade instructions.
 414
 415 For notes on 1.26.x and older releases, see HISTORY.
 416
 417 == Online documentation ==
 418
 419 Documentation for both end-users and site administrators is available on
 420 MediaWiki.org, and is covered under the GNU Free Documentation License (except
 421 for pages that explicitly state that their contents are in the public domain):
 422
 423        https://www.mediawiki.org/wiki/Documentation
 424
 425 == Mailing list ==
 426
 427 A mailing list is available for MediaWiki user support and discussion:
 428
 429        https://lists.wikimedia.org/mailman/listinfo/mediawiki-l
 430
 431 A low-traffic announcements-only list is also available:
 432
 433        https://lists.wikimedia.org/mailman/listinfo/mediawiki-announce
 434
 435 It's highly recommended that you sign up for one of these lists if you're
 436 going to run a public MediaWiki, so you can be notified of security fixes.
 437
 438 == IRC help ==
 439
 440 There's usually someone online in #mediawiki on irc.freenode.net.