TYPO3 Exception 1338996122

Package "..." is already registered.

Accidental double install

When installing extensions twice (for example by inadvertently using a copied folder) this exception might occur. To get rid of it again, remove the extension from the typo3conf/PackageStates.php manually.

Duplicate composer.json package name:

Another package uses the same name in its composer.json file. Even if composer mode is not enabled and the composer file is just copied, it will cause the TYPO3 Package Manager to throw the correct exception. This may happen if you copy an extension, e.g. from typo3conf/ext/acme to typo3conf/ext/acme.old. Just search the filesystem for any other instances of the same package name and rename one of them.