Problem

I recently upgraded to Jenkins version 2.504.2 and plugin version 1356.ve360da_6c523a_.

When trying to "Save" a job config, the change message popup appears. Whether I put a message in or not, and click "Save", the modal disappears and no activity happens (no page redirect, error or success message).

Upon further inspection, a javascript error occurs (see screenshot) and no network activity is shown for the request to save the changes. Error screenshot:

mandatory-config-reason.js:77 An invalid form control with name='_.artifactNumToKeepStr' is not focusable. <input step=​"1" min=​"1" name=​"_.artifactNumToKeepStr" type=​"number" class=​"jenkins-input  positive-number" value=​"0">​
handleClick @ mandatory-config-reason.js:77
dialog.prompt.then.dialogShown @ mandatory-config-reason.js:65 

The "Apply" button does not seem to be impacted in the same way.

After I disabled the "Show change message dialog in config pages for jobs and agents" setting, the issue has been resolved.

Based on the error message, this is potentially caused by the build discarder plugin, but I dont think that fully explains the issue, since "Apply" seems to work just fine, as well as when the change message popup is disabled.