Settings > Sharing doesn't load (shows white page)

Hi everyone,

because I wasn’t able to share folders with other users in my Nextcloud installation, I wanted to check the settings for sharing. But when opening the sharing settings, it only shows a blank (white) page.

Chrome shows me this error message in the console:

Failed to load resource: cloud/data/.ocdata?t=1552073149566
the server responded with a status of 403 ()

The last message in the logs is 2 days old, so I guess there are none regarding this problem.

Nextcloud version: 15.0.5
PHP Version: 7.2