I would try purging caches before you do anything else...
Howard Miller
Posts made by Howard Miller
This is a problem with your PHP installation, not Moodle.
The function, https://www.php.net/manual/en/intlgregoriancalendar.setgregorianchange.php, is missing in your PHP. This would imply a problem with the Intl extension. Fixing this depends on how you are hosted and how PHP was installed.
The function, https://www.php.net/manual/en/intlgregoriancalendar.setgregorianchange.php, is missing in your PHP. This would imply a problem with the Intl extension. Fixing this depends on how you are hosted and how PHP was installed.
Please enable Debugging (all the way to developer and display errors) and get us the full error trace 
Waking the dead here, but I wrote something similar and *do* support it (well, try to)
https://moodle.org/plugins/report_assign
https://moodle.org/plugins/report_assign
"I already uninstalled all plugins via CLI"
What, exactly, did you do?
What, exactly, did you do?