Getting 504 Gateway Time-out Error while accessing A few jobs in Jenkins

We have recently upgarded the jenkins to 2.387.1 version. Post upgradation we are getting 504 Gateway Time-out Error while accessing some jobs. Mostly jobs we are able to access but a few jobs give 504 Gateway Time-out. Once we kill the current executing thread for a job from monitoring section, all jobs were accessible.
Kindly help me out to find the root cause for the issue or help me out with a solution to fix this issue.

Are you accessing Jenkins from reverse proxy?

:point_up: jenkins has no gateway to time out. Likely ELB or Reverse Proxy, or even a general proxy is the cause.

That being said, something will be in some log somewhere, I would recommend starting with your jenkins server log (journalctl -u jenkins.service in linux) to see what errors its spitting out and try to address thm.

My general recommendation is to upgrade all plugins (GitHub - jenkinsci/plugin-installation-manager-tool: Plugin Manager CLI tool for Jenkins if you can’t access the gui) and follow the Jenkins LTS Upgrade Guide if you can.

Also note that depending on which version you upgraded to, java 11 is now required.