Errors in log-file and slow site

My installation seems very slow. In the log-file I find many of these errors.

Error PHP Method OC_L10N_String::__toString() must return a string value at /storage/content/16/113316/

Error PHP vsprintf(): Too few arguments at /storage/content/16/113316/

Any explanation?

Can you tell us what version of Nextcloud you are using and what system you have? Which php version? You installed all required modules (check the documentation)?

Installed on a shared server with PhP 7.0 and MySql by the webb-installer NC version 12.0.3… How can I now if all required modules are installed?

A script with <?php phpinfo(); ?> in the document root should give you the whole configuration of your php setup.

Why I asked about the Nextcloud version is that there was a similiar report in previous versions ( Since last time it was related to the activity app, you could try to disable if it runs better then. If the problem persists with Nextcloud 12.0.4, please report this to the bug tracker on

Can you explain more about how to place that script - I guess it must be in a file? Where is the document root?