Adding a new Backupclient the server crashed

Hi all,
If I add a new client, the server is crashing. I tried it with a windows client and a linux client.
In the Urbackup-Serverlogs I can only see:

2023-08-19 13:18:27: Authed+capa for client '' (encrypted-v2, compressed-zstd) - 1 spare connections
2023-08-19 13:18:27: New Backupclient:

Nothing happend after this entry.
The WebUI is not available anymore.
In the Syslog is nothing.

The server service is still active:

● urbackupsrv.service - LSB: Server for doing backups
     Loaded: loaded (/etc/init.d/urbackupsrv; generated)
     Active: active (exited) since Sat 2023-08-19 12:37:24 CEST; 49min ago
       Docs: man:systemd-sysv-generator(8)
    Process: 6097 ExecStart=/etc/init.d/urbackupsrv start (code=exited, status=>
        CPU: 24.409s

If I will stop the client service, I need to restart the server. After that the server is working correct.
I tried the remove-unknown already.

Anyone an idea?

Anyone an idea?