The server was unable to complete your request

Hello guys,

I am new to nextcloud. Followed some instalation guides on github and i have the following problem:
After installation, i can log on with the admin account and also create another account and log with it but after few clicks and going through the menu (using the admin account) and then logoff, when again logging in it does not work anymore, but only with the admin account. The error:

The log line:
{“reqId”:“HA3OTDKmyOolbU22cBIj”,“level”:3,“time”:“2020-05-14T17:55:28+00:00”,“remoteAddr”:“172.20.20.254”,“user”:“QesAXGzkB”,“app”:“index”,“method”:“GET”,“url”:"/index.php/apps/files/",“message”:{“Exception”:“OCP\Files\NotFoundException”,“Message”:"",“Code”:0,“Trace”:[{“file”:"/snap/nextcloud/20498/htdocs/apps/files/lib/Controller/ViewController.php",“line”:139,“function”:“getStorageInfo”,“class”:“OC_Helper”,“type”:"::",“args”:["/",false]},{“file”:"/snap/nextcloud/20498/htdocs/apps/files/lib/Controller/ViewController.php",“line”:187,“function”:“getStorageInfo”,“class”:“OCA\Files\Controller\ViewController”,“type”:"->",“args”:[]},{“file”:"/snap/nextcloud/20498/htdocs/lib/private/AppFramework/Http/Dispatcher.php",“line”:170,“function”:“index”,“class”:“OCA\Files\Controller\ViewController”,“type”:"->",“args”:["","",null,false]},{“file”:"/snap/nextcloud/20498/htdocs/lib/private/AppFramework/Http/Dispatcher.php",“line”:99,“function”:“executeController”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Files\Controller\ViewController”},“index”]},{“file”:"/snap/nextcloud/20498/htdocs/lib/private/AppFramework/App.php",“line”:125,“function”:“dispatch”,“class”:“OC\AppFramework\Http\Dispatcher”,“type”:"->",“args”:[{“class”:“OCA\Files\Controller\ViewController”},“index”]},{“file”:"/snap/nextcloud/20498/htdocs/lib/private/AppFramework/Routing/RouteActionHandler.php",“line”:47,“function”:“main”,“class”:“OC\AppFramework\App”,“type”:"::",“args”:[“OCA\Files\Controller\ViewController”,“index”,{“class”:“OC\AppFramework\DependencyInjection\DIContainer”},{"_route":“files.view.index”}]},{“function”:"__invoke",“class”:“OC\AppFramework\Routing\RouteActionHandler”,“type”:"->",“args”:[{"_route":“files.view.index”}]},{“file”:"/snap/nextcloud/20498/htdocs/lib/private/Route/Router.php",“line”:299,“function”:“call_user_func”,“args”:[{“class”:“OC\AppFramework\Routing\RouteActionHandler”},{"_route":“files.view.index”}]},{“file”:"/snap/nextcloud/20498/htdocs/lib/base.php",“line”:1008,“function”:“match”,“class”:“OC\Route\Router”,“type”:"->",“args”:["/apps/files/"]},{“file”:"/snap/nextcloud/20498/htdocs/index.php",“line”:38,“function”:“handleRequest”,“class”:“OC”,“type”:"::",“args”:[]}],“File”:"/snap/nextcloud/20498/htdocs/lib/private/legacy/helper.php",“Line”:490,“CustomMessage”:"–"},“userAgent”:“Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.138 Safari/537.36”,“version”:“18.0.4.2”}

My setup consists in:
-nextcloud snap installed on ubuntu server 18.04
-i mapped a cifs share on the machine with 0770 privileges
-i moved the data directory to this share
-i added ‘filesystem_check_changes’ => 1, in the php config file so the files get scaned automatically because i had this problem
-the only app i enabled on the machine is the external drive app; all the rest of them are the default.
-snap nextcloud version installed is the latest one in this moment

I rebooted the machine, reverted to earlier snapshots, retried all the steps, but i always reach this one. Sometimes the error appears earlier, sometimes appears after a day o usage, or few hours, etc. I could not find a pattern in its repeating.

Thank you