Breaking: #82377 - Option to allow uploading system extensions removed

See forge#82377


The option to allow uploading additional extensions as system extensions in TYPO3 has been removed without substitution.

Disclaimer: It is highly discouraged by the TYPO3 Core to modify anything within typo3/sysext/, especially adding extensions, as typo3conf/ is the folder to add or override extensions.

If an administrator needs to do changes within typo3/sysext/ it's at his/her own risk, and should not be encouraged to be possible from TYPO3 itself.


The possibility to upload an extension into typo3/sysext/ via the Extension Manager / TYPO3 Backend interface is removed. System extensions can only be added or modified via the file system now.

Affected Installations

TYPO3 instances having the option $GLOBALS['TYPO3_CONF_VARS']['EXT']['allowSystemInstall'] enabled and do not run in TYPO3's Composer Mode.

As this option was disabled by default for over 10 years, it is highly unlikely this change will affect a regular instance.


The mentioned option, if set, is automatically removed when accessing the Install Tool through the SilentMigrationService.