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Some or all of the below information will be requested if it isn’t supplied; for fastest response please provide as much as you can 
Nextcloud version (eg, 20.0.5): 23.0.2 installed via Snap
Operating system and version (eg, Ubuntu 20.04): Ubuntu 16.04
Apache or nginx version (eg, Apache 2.4.25): Unknown (included in snap package)
PHP version (eg, 7.4): Unknown (included in snap package)
The issue you are facing:
- After snap decided to auto-upgrade Nextcloud from version 22 to 23, no users are able to login, since we are depending on the user_saml app which was auto-disabled during the upgrade process.
- I have learned that the user_saml app is not compatible with Nextcloud 23 yet.
- I also understand that downgrading to a previous version of Nextcloud is not supported.
- On the Github issue for adding NC 23 support to user_saml, there is a comment about running
occ app:enable -f user_samlto force the app to be enabled anyway. However, there is also a comment upcoming config format changes that need to be resolved before the app is ready for NC 23, which makes me hesitant to run this command.
Is this the first time you’ve seen this error? (Y/N): Y
Steps to replicate it:
- Install Nextcloud 22 or earlier
- Enable user_saml app and create a new user with only SAML login
- Delete the initial admin user
- Upgrade to Nextcloud 23
- There are now no users in your system, nobody can login.
nextcloud.occ user:listshows that the SAML-users do not exist anymore (but their files still seem to be in the storage folder.)
The output of your Nextcloud log in Admin > Logging:
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::maintenanceEnabled: Turned on maintenance mode","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":0,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"core","method":"","url":"--","message":"starting upgrade from 22.2.5.1 to 23.0.2.1","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Deprecated event type for \\OC\\Repair::step: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Repair::step: Repair step: Repair MySQL collation","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Deprecated event type for \\OC\\Repair::info: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Repair::info: Repair info: All tables already have the correct collation -> nothing to do","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Deprecated event type for \\OC\\Repair::step: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Repair::step: Repair step: Repair SQLite autoincrement","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Deprecated event type for \\OC\\Repair::step: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:35+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Repair::step: Repair step: Copy data from accounts table when migrating from ownCloud","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:36+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"Deprecated event type for \\OC\\Repair::step: Symfony\\Component\\EventDispatcher\\GenericEvent is used","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:36+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Repair::step: Repair step: Drop account terms table when migrating from ownCloud","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:36+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::dbUpgradeBefore: Updating database schema","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:45+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::dbUpgrade: Updated database","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:45+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::incompatibleAppDisabled: Disabled incompatible app: files_automatedtagging","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:45+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::incompatibleAppDisabled: Disabled incompatible app: files_retention","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":1,"time":"2022-03-16T05:09:45+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::incompatibleAppDisabled: Disabled incompatible app: user_saml","userAgent":"--","version":"22.2.5.1"}
...
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":0,"time":"2022-03-16T05:09:50+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::checkAppStoreAppBefore: Checking for update of app \"user_saml\" in appstore","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":0,"time":"2022-03-16T05:09:50+00:00","remoteAddr":"","user":"--","app":"updater","method":"","url":"--","message":"\\OC\\Updater::checkAppStoreApp: Checked for update of app \"user_saml\" in appstore","userAgent":"--","version":"22.2.5.1"}
{"reqId":"X5TUPGsKEkBMSD9UafGr","level":3,"time":"2022-03-16T05:09:50+00:00","remoteAddr":"","user":"--","app":"no app in context","method":"","url":"--","message":"App \"SSO & SAML authentication\" cannot be installed because it is not compatible with this version of the server.","userAgent":"--","version":"22.2.5.1","exception":{"Exception":"Exception","Message":"App \"SSO & SAML authentication\" cannot be installed because it is not compatible with this version of the server.","Code":0,"Trace":[{"file":"/snap/nextcloud/29929/htdocs/lib/private/legacy/OC_App.php","line":440,"function":"installApp","class":"OC\\Installer","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/lib/private/Updater.php","line":424,"function":"enable","class":"OC_App","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/lib/private/Updater.php","line":277,"function":"upgradeAppStoreApps","class":"OC\\Updater","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/lib/private/Updater.php","line":133,"function":"doUpgrade","class":"OC\\Updater","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/core/Command/Upgrade.php","line":235,"function":"upgrade","class":"OC\\Updater","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/3rdparty/symfony/console/Command/Command.php","line":255,"function":"execute","class":"OC\\Core\\Command\\Upgrade","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/3rdparty/symfony/console/Application.php","line":1009,"function":"run","class":"Symfony\\Component\\Console\\Command\\Command","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/3rdparty/symfony/console/Application.php","line":273,"function":"doRunCommand","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/3rdparty/symfony/console/Application.php","line":149,"function":"doRun","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/lib/private/Console/Application.php","line":211,"function":"run","class":"Symfony\\Component\\Console\\Application","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/console.php","line":99,"function":"run","class":"OC\\Console\\Application","type":"->"},{"file":"/snap/nextcloud/29929/htdocs/occ","line":11,"args":["/snap/nextcloud/29929/htdocs/console.php"],"function":"require_once"}],"File":"/snap/nextcloud/29929/htdocs/lib/private/Installer.php","Line":132,"CustomMessage":"App \"SSO & SAML authentication\" cannot be installed because it is not compatible with this version of the server."}}
Are there any ways out of this situation that will not bring more problems later? Other than waiting for a new version of the app?