login on calendarserver.php not working

[nightflyer88]

I set up the Caldav example on a public web server (https://xxxxxx.ch/calendarserver.php/). In the login prompt, I enter the standard user/password (admin/admin), but the login doesn't work. There are no errors. I tested the PHP connection to the Sabredav database and it works.

I also tested the example with XAMPP locally and it works, just not on the public server.

Any ideas? What should the database format be? I have utf8mb4_general_ci.

PHP version: 8.2.27 with FPM/FastCGI