Personal settings raises error, can't share folder with other users/group

Nextcloud version: 12.0.3
Operating system and version: Ubuntu 14.04 - nextcloud installed from downloaded package from
Apache or nginx version : 2.4.27
PHP version : 7.0.24
Is this the first time you’ve seen this error?: Yes

Can you reliably replicate it? (If so, please outline steps): Yes, error happen every time when trying to open "Settings -> Personal"
Have tried to disable and enable Federation plugin - happen in both situations.
This migrated installation from many previous owncloud version. Everything worked fine at OwnCloud version 10.x

Additionally, folder sharing option with local users/group does not exist even is enabled in settings. Not sure if it is related to Federation plugin.

The issue you are facing:
Internal Server Error

The server encountered an internal error and was unable to complete your request.

Please contact the server administrator if this error reappears multiple times, please include the technical details below in your report.

More details can be found in the server log.

Technical details

Remote Address: <IP>
Request ID: MpXwqJaAnvhEQnb4EIEe
Type: Error
Code: 0
Message: Class 'OCA\FederatedFileSharing\AppInfo\Application' not found
File: /var/www/nextcloud/settings/personal.php
Line: 223


#0 /var/www/nextcloud/lib/private/Route/Route.php(155) : runtime-created function(1): require_once()
#1 [internal function]: __lambda_func(NULL)
#2 /var/www/nextcloud/lib/private/Route/Router.php(299): call_user_func(’\x00lambda_468’, Array)
#3 /var/www/nextcloud/lib/base.php(1004): OC\Route\Router->match(’/settings/perso…’)
#4 /var/www/nextcloud/index.php(48): OC::handleRequest()
#5 {main}

The output of your Nextcloud log in Admin > Logging:
Empty page is returned for: index.php/settings/admin/logging

Any news here? Same Error after upgrade from OC 10.0.1 to NC 12.0.3…

could we please get any attention?
I’m happy to review issue/debug and provide more details. Would need to get folder sharing working relatively soon as otherwise will have to move back to ownCloud.

See steps here: Next Cloud Share repair. Steps as at the bottom helped me. In essence, NextCloud re-installation and restore of data + some manual steps. No need to move anything from “apps” folder.