TYPO3 Core

Reported by Aristeidis Karavas (Apr 28th at 11:51) via Slack:
https://typo3.slack.com/archives/C025BQLFA/p1588067478426300

Why in TYPO3 v10 this won't set the meta tags in frontend?
$metaTag = $this->metaTagManagerRegistry->getManagerForProperty($key);
$metaTag->addProperty($key, $metaTagValue);
If i debug it, it sets everything right but it won't be displayed in the frontend

The reason is that the PageRenderer stores a new Singleton via GeneralUtility::setSingletonInstance in __wakeup.

That updates MetaTagManagerRegistry instances retrieved via GeneralUtility::makeInstance, but not those injected via symfony DI,
where the object will already have been generated, as it is loaded during EXT:seo/ext_localconf.php loading and GeneralUtility::makeInstance
will call the DI container.

This issues happens when the PageRenderer was serialized and is unserialized for USER_INT plugins (e.g. uncached extbase plugins).

Same applies to AssetCollector, which is serialized and unserialized as well.