Two kinds of errors appeared during a deployment earlier today.
These was limited to one server (mw1262), one PHP run-time PHP 7, and recovered within a minute or two. This suggests it's related to opcache corruption or some such.
See also: T221347
>>! **Fatal error due to undefined interface**
>
> Request ID: `XO1PdwpAADkAAAL-DwYAAABE`
>
> ```name=message
> [{exception_id}] {exception_url} PHP Fatal Error from line 29 of /srv/mediawiki/php-1.34.0-wmf.6/vendor/wikibase/data-model/src/Entity/Item.php: Interface 'Wikibase\DataModel\Statement\StatementListHolder' not found
> ```
> It seems there is no useful stacktrace. Ping T187147.
>>! **PHP error - undefined key**
>
> Request ID: `XO1PcgpAADkAAAL-Do8AAABA`
>
> ```name=message,lines=2
> PHP Notice: Undefined index: userlangattributes
>
> #0 /srv/mediawiki/php-1.34.0-wmf.6/includes/skins/QuickTemplate.php(117): MWExceptionHandler::handleError(integer, string, string, integer, array)
> #1 /srv/mediawiki/php-1.34.0-wmf.6/skins/Vector/includes/VectorTemplate.php(229): QuickTemplate->html(string)
> #2 /srv/mediawiki/php-1.34.0-wmf.6/skins/Vector/includes/VectorTemplate.php(205): VectorTemplate->renderPortal(string, array)
> #3 /srv/mediawiki/php-1.34.0-wmf.6/skins/Vector/includes/VectorTemplate.php(118): VectorTemplate->renderPortals(array)
> #4 /srv/mediawiki/php-1.34.0-wmf.6/includes/skins/SkinTemplate.php(230): VectorTemplate->execute()
> #5 /srv/mediawiki/php-1.34.0-wmf.6/includes/OutputPage.php(2749): SkinTemplate->outputPage()
> #6 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWException.php(180): OutputPage->output()
> #7 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWException.php(216): MWException->reportHTML()
> #8 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWExceptionHandler.php(119): MWException->report()
> #9 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWExceptionHandler.php(195): MWExceptionHandler::report(MWException)
> #10 /srv/mediawiki/php-1.34.0-wmf.6/includes/MediaWiki.php(542): MWExceptionHandler::handleException(MWException)
> #11 /srv/mediawiki/php-1.34.0-wmf.6/index.php(42): MediaWiki->run()
> ```
> Appears to be PHP 7 specific somehow, which is unusual for this type of error.
>>! From {T224493}
>
> Error from line 448 of /srv/mediawiki/php-1.34.0-wmf.6/includes/CommentStore.php: Call to undefined method CommentStore::getCommentInternal()
>
> | Count| 2,256
> | Duration| 13:59 - 14:09 (10 mintes)
> | Host(s)| `mw1329`
>>! **Call to undefined method PermissionManager::checkPageRestrictions()**
>
> ```name=message,lines=5
> [{exception_id}] {exception_url} Error from line 264 of /srv/mediawiki/php-1.34.0-wmf.6/includes/Permissions/PermissionManager.php: Call to undefined method MediaWiki\Permissions\PermissionManager::checkPageRestrictions()
>
> #0 /srv/mediawiki/php-1.34.0-wmf.6/includes/Permissions/PermissionManager.php(117): MediaWiki\Permissions\PermissionManager->getPermissionErrorsInternal(string, User, Title, string, boolean)
> #1 /srv/mediawiki/php-1.34.0-wmf.6/includes/Title.php(2217): MediaWiki\Permissions\PermissionManager->userCan(string, User, Title, string)
> #2 /srv/mediawiki/php-1.34.0-wmf.6/includes/Title.php(2185): Title->userCan(string, User, string)
> #3 /srv/mediawiki/php-1.34.0-wmf.6/includes/skins/SkinTemplate.php(987): Title->quickUserCan(string, User)
> #4 /srv/mediawiki/php-1.34.0-wmf.6/includes/skins/SkinTemplate.php(464): SkinTemplate->buildContentNavigationUrls()
> #5 /srv/mediawiki/php-1.34.0-wmf.6/includes/skins/SkinTemplate.php(228): SkinTemplate->prepareQuickTemplate()
> #6 /srv/mediawiki/php-1.34.0-wmf.6/includes/OutputPage.php(2749): SkinTemplate->outputPage()
> #7 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWExceptionRenderer.php(134): OutputPage->output()
> #8 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWExceptionRenderer.php(53): MWExceptionRenderer::reportHTML(Error)
> #9 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWExceptionHandler.php(121): MWExceptionRenderer::output(Error, integer)
> #10 /srv/mediawiki/php-1.34.0-wmf.6/includes/exception/MWExceptionHandler.php(195): MWExceptionHandler::report(Error)
> #11 /srv/mediawiki/php-1.34.0-wmf.6/includes/MediaWiki.php(545): MWExceptionHandler::handleException(Error)
> #12 /srv/mediawiki/php-1.34.0-wmf.6/index.php(42): MediaWiki->run()
> ```
>
> | Count|1,974
> |Host| mw1273
> |Duration| 15-20 minutes