[Koha] Service unavailable

[Beda Szukics]

Hello

I'm running 4 instances of Koha on 1 server. 3 work fine, the 4th gives me:

Service Unavailable

The server is temporarily unable to service your request due to 
maintenance downtime or capacity problems. Please try again later.
Apache/2.4.38 (Debian) Server at bibliotheksverwaltung.abtei-muri.ch 
Port 443

/var/log/koha/mg/intranet-error.log tells me:

[Wed Nov 08 07:35:21.555396 2023] [proxy:error] [pid 18177] (2)No such 
file or directory: AH02454: HTTP: attempt to connect to Unix domain 
socket /var/run/koha/mg/plack.sock (localhost) failed
[Wed Nov 08 07:35:21.555491 2023] [proxy_http:error] [pid 18177] [client 
84.18.155.129:63022] AH01114: HTTP: failed to make connection to 
backend: httpd-UDS

Where is the problem?

I migrated this instance from a second server using koha-restore

Greetings

Beda