With the help of Upgrade issue v20 -> v21: OCC no longer works because of Undefined class constant 'MAJOR_VERSION' in /var/www/nextcloud/3rdparty/guzzlehttp/guzzle/src/Utils.php:118 路 Issue #1834 路 nextcloud/vm 路 GitHub I fixed the error by removing the apps files_external_gdrive, sendent, camerarawpreviews and checksum from the hard drive and from the config.php. Now it works