I've got the same problem, after updating to 2.1.0 the admin interface wasn't accessible anymore, showing this message:
Domain not configured
This domain requires configuration via the froxlor server management panel, as it is currently not assigned to any customer.
Now i did an update to 2.1.1 and the situation didn't change. Still the same message, and everything I tried to do had no effect at all (i.eg. switching the document root directly into the froxlor directory)
The point is, the vhost of the froxlor admin interface is manually configured. I don't want the admin interface to be depenmdent from a configuration I have to do inside the admin interface.
The Installation that is causing touble is running on Debian 11. In parallel I've got a newer host, running on Debian 12, that is going to replace the Debian 11 installation, which is running fine with Froxlor 2.1.1.
I tried to fiugre out what froxlor needs to work properly, but I didn't find any problem. The only thing that is visible is, that a request on index.php throws status 302 and redirects the request to /froxlor/notice.html
176.199.24.215 - <httpuser> [11/Dec/2023:09:19:17 +0100] "GET /froxlor/ HTTP/1.1" 302 3909 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36"
176.199.24.215 - <httpuser> [11/Dec/2023:09:19:17 +0100] "GET /froxlor/notice.html HTTP/1.1" 200 5545 "-" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36"
Any Ideas???
cheers
Sandro