```
[08a09c9f4968bff42dd6c232] [no req] MWContentSerializationException from line 299 of /srv/mediawiki/php-1.33.0-wmf.18/extensions/Wikibase/lib/includes/Store/EntityContentDataCodec.php: $entityId and $targetId can not be the same.
Backtrace:
#0 /srv/mediawiki/php-1.33.0-wmf.18/extensions/Wikibase/repo/includes/Content/EntityHandler.php(384): Wikibase\Lib\Store\EntityContentDataCodec->decodeRedirect(string, string)
#1 /srv/mediawiki/php-1.33.0-wmf.18/extensions/Wikibase/repo/includes/Content/EntityHandler.php(308): Wikibase\Repo\Content\EntityHandler->unserializeContent(string, string)
#2 /srv/mediawiki/php-1.33.0-wmf.18/includes/export/XmlDumpWriter.php(257): Wikibase\Repo\Content\EntityHandler->exportTransform(string, string)
#3 /srv/mediawiki/php-1.33.0-wmf.18/includes/export/WikiExporter.php(471): XmlDumpWriter->writeRevision(stdClass)
#4 /srv/mediawiki/php-1.33.0-wmf.18/includes/export/WikiExporter.php(431): WikiExporter->outputPageStreamBatch(Wikimedia\Rdbms\ResultWrapper, stdClass)
#5 /srv/mediawiki/php-1.33.0-wmf.18/includes/export/WikiExporter.php(256): WikiExporter->dumpPages(string, boolean)
#6 /srv/mediawiki/php-1.33.0-wmf.18/includes/export/WikiExporter.php(141): WikiExporter->dumpFrom(string, boolean)
#7 /srv/mediawiki/php-1.33.0-wmf.18/maintenance/includes/BackupDumper.php(280): WikiExporter->pagesByRange(integer, integer, boolean)
#8 /srv/mediawiki/php-1.33.0-wmf.18/maintenance/dumpBackup.php(83): BackupDumper->dump(integer, integer)
#9 /srv/mediawiki/php-1.33.0-wmf.18/maintenance/doMaintenance.php(94): DumpBackup->execute()
#10 /srv/mediawiki/php-1.33.0-wmf.18/maintenance/dumpBackup.php(138): require_once(string)
#11 /srv/mediawiki/multiversion/MWScript.php(100): require_once(string)
#12 {main}
```
Reproduction case: https://test.wikidata.org/w/index.php?title=Q193394&redirect=no
Req ID: `AWk0u32gjSm8tOlx-BX_`
Stacktrace for that web request:
```
#0 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/repo/includes/Content/EntityHandler.php(384): Wikibase\Lib\Store\EntityContentDataCodec->decodeRedirect(string, NULL)
#1 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/RevisionStore.php(1472): Wikibase\Repo\Content\EntityHandler->unserializeContent(string, NULL)
#2 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/RevisionStore.php(1634): MediaWiki\Revision\RevisionStore->loadSlotContent(MediaWiki\Revision\SlotRecord, NULL, NULL, NULL, integer)
#3 [internal function]: Closure$MediaWiki\Revision\RevisionStore::loadSlotRecords(MediaWiki\Revision\SlotRecord)
#4 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/SlotRecord.php(307): call_user_func(Closure$MediaWiki\Revision\RevisionStore::loadSlotRecords;2106, MediaWiki\Revision\SlotRecord)
#5 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/RevisionRecord.php(175): MediaWiki\Revision\SlotRecord->getContent()
#6 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision.php(923): MediaWiki\Revision\RevisionRecord->getContent(string, integer, User)
#7 /srv/mediawiki/php-1.33.0-wmf.19/includes/page/Article.php(494): Revision->getContent(integer, User)
#8 /srv/mediawiki/php-1.33.0-wmf.19/includes/page/Article.php(714): Article->fetchRevisionRecord()
#9 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/repo/includes/Actions/ViewEntityAction.php(79): Article->view()
#10 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/repo/includes/Actions/ViewEntityAction.php(54): Wikibase\ViewEntityAction->showEntityPage()
#11 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(501): Wikibase\ViewEntityAction->show()
#12 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title)
#13 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(867): MediaWiki->performRequest()
#14 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(517): MediaWiki->main()
#15 /srv/mediawiki/php-1.33.0-wmf.19/index.php(42): MediaWiki->run()
#16 /srv/mediawiki/w/index.php(3): include(string)
#17 {main}
```
Note there is also a field `exception.previous.trace`:
```
#0 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/lib/includes/Store/EntityContentDataCodec.php(296): Wikibase\DataModel\Entity\EntityRedirect->__construct(Wikibase\DataModel\Entity\ItemId, Wikibase\DataModel\Entity\ItemId)
#1 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/repo/includes/Content/EntityHandler.php(384): Wikibase\Lib\Store\EntityContentDataCodec->decodeRedirect(string, NULL)
#2 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/RevisionStore.php(1472): Wikibase\Repo\Content\EntityHandler->unserializeContent(string, NULL)
#3 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/RevisionStore.php(1634): MediaWiki\Revision\RevisionStore->loadSlotContent(MediaWiki\Revision\SlotRecord, NULL, NULL, NULL, integer)
#4 [internal function]: Closure$MediaWiki\Revision\RevisionStore::loadSlotRecords(MediaWiki\Revision\SlotRecord)
#5 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/SlotRecord.php(307): call_user_func(Closure$MediaWiki\Revision\RevisionStore::loadSlotRecords;2106, MediaWiki\Revision\SlotRecord)
#6 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision/RevisionRecord.php(175): MediaWiki\Revision\SlotRecord->getContent()
#7 /srv/mediawiki/php-1.33.0-wmf.19/includes/Revision.php(923): MediaWiki\Revision\RevisionRecord->getContent(string, integer, User)
#8 /srv/mediawiki/php-1.33.0-wmf.19/includes/page/Article.php(494): Revision->getContent(integer, User)
#9 /srv/mediawiki/php-1.33.0-wmf.19/includes/page/Article.php(714): Article->fetchRevisionRecord()
#10 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/repo/includes/Actions/ViewEntityAction.php(79): Article->view()
#11 /srv/mediawiki/php-1.33.0-wmf.19/extensions/Wikibase/repo/includes/Actions/ViewEntityAction.php(54): Wikibase\ViewEntityAction->showEntityPage()
#12 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(501): Wikibase\ViewEntityAction->show()
#13 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title)
#14 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(867): MediaWiki->performRequest()
#15 /srv/mediawiki/php-1.33.0-wmf.19/includes/MediaWiki.php(517): MediaWiki->main()
#16 /srv/mediawiki/php-1.33.0-wmf.19/index.php(42): MediaWiki->run()
#17 /srv/mediawiki/w/index.php(3): include(string)
#18 {main}
```