Issue A lot of random "500 Internal Server Error" from nginx since March 10th

[King555]

Server operating system version

Ubuntu 24.04.2 LTS

Plesk version and microupdate number

Plesk Obsidian 18.0.68 Update #1 Web Admin Edition

Since several days, this is since March 10th, my sites are randomly down for a few minutes with the message "500 Internal Server Error", which comes from nginx. Today the nginx service also was shutdown and Watchdog released it from monitoring (which led to a timeout instead of the error message). The error 500 comes mostly on single sites, so not on all at once. But always different sites (completely random).

I don't think that nginx got an update in the last weeks. But I installed all the other updates which were available for Plesk and my operating system, max. 24 h after their availability for my system.

The only log entry I could find is this:

Stopping nginx.service - Startup script for nginx service...
nginx.service: Deactivated successfully.
Stopped nginx.service - Startup script for nginx service.
nginx.service: Consumed 9h 29min 51.852s CPU time, 172.0M memory peak, 0B memory swap peak.

Does anyone else experienced this kind of problem in the last weeks?

 

[mow]

What are your hosting settings? Do you use nginx only or as reverse proxy?

 

[King555]

I use nginx only as a reverse proxy, my main web server is Apache. All web server specific settings are the Plesk defaults.

 

[King555]

Today nginx crashes nonstop since a few hours. I see these error messages in /var/log/nginx/error.log:

[alert] 3824807#0: socket() failed (24: Too many open files) while requesting certificate status, responder: r10.o.lencr.org, peer: [2001:2030:21::3e73:fc59]:80, certificate: "/opt/psa/var/certificates/scf29GeRI"

[emerg] 23706#0: open() "/var/www/vhosts/system/example.com/logs/proxy_access_ssl_log" failed (30: Read-only file system)

I have no idea whether these errors have something to do with the crashes.

I also restarted the whole server, but that did not solve the problem at all.

 

[mow]

I use nginx only as a reverse proxy, my main web server is Apache. All web server specific settings are the Plesk defaults.

Then the 500 actually comes from Apache. Check the Apache error log. (/var/www/vhosts/system/yourdomain/logs/error_log)

 

[mow]

I also restarted the whole server, but that did not solve the problem at all.

Is that a real server or just a vhost?

 

[King555]

I thought the error comes from nginx, because nginx is mentioned in the error message in the browser. Also nginx crahes all the time, Apache doesn't.

And it's a dedicated (real) server.

I will check the logs.