Openproject after update not reachable on xxxxx/openproject/

We run UCS on 4.3.2 and have openproject installed on it. Since we made a minor upgrade yesterday through the ucs backend, openproject is “service unavailable” in the browser. UCS says it is running. I can stop and start the app also, but no change in the browser.

It worked all fine until yesterday evening. No additional changes done to the system. I am thankful for every help.

Best, Sam

Sorry, I forgot: this is the error message. we run it on https.

Service Temporarily Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Apache/2.2.22 (Univention) Server at Port 80

guys, is there no advice for any log or something, I can check? I am greateful for any help. Thanks a lot.