UPDATE: After updating all remaining plugins the issue seems to be fixed.
Keeping explanation of issue below.
I think I see same kind of UI behaviour as Bob mentioned.
What I did
- Backup version: Jenkins LTS 2.401.1
- Installed Jenkins LTS 2.426.3 on a different host
- Applied the backup of Jenkins LTS 2.401.1
My backup consisted of
- all jobs (excluding builds dir for each job)
- Exlude following dirs: war, cache, tools, workspace
In my case the job configurations look unchanged, but sections which should be collapsed are expanded. The attached screenshot offers better explanation I hope.
I'm not able to duplicate the problem as described. "How to report an issue" provides guidance on the type of information that is needed so that others can duplicate the problem.
It is possible that one or more of the plugin versions installed on your controller needs to be updated. If you haven't updated to the most recent releases of all the plugins you are using, that is a good first step.
If the problem persists after updating all the plugins to their most recent releases, refer to configuration form modernization diagnosis steps for more ideas of things that you can check.