Hello owncloud user (and thanks the developer!). I use owncloud on the german service provider STRATO. To sync my calendar, my contacts and so on.
I updated my owncloud to version 10.0.6. Procedure: I allways place the new version on the server, my data to and replace the config.php.
But then I got an error message: PHP module is not installed or any other reason.
I solved the problem: it was an issue with the php version. Owncloud 10.0.6 seems not to work with php 7.1. So I change the running version to php 7.2.1 - and Ownclud works now fine again.
Maybe that helps somebody. It tooks me a few hours to ponder.