Can you be clearer on the issue?

is it the whole pipeline syntax or just the audit trail plugin?

Screen shots?

Is there any errors in the browser console?

This seems to be caused by a security fix in Audit trail. I am able to reproduce this in an environment where Audit Trail was upgraded. I see an Administrative Monitor that points to (https://github.com/jenkinsci/audit-trail-plugin/blob/master/docs/bypassable-patterns.adoc). And hitting "Apply default pattern" fixes this. Maybe Audit trail is blocking some requests with the legacy pattern.

Will there be any impact if we "Apply default pattern?" Having the below error:

prukamar this monitor is not an error but a warning indicating that the pattern you are using with audit trail plugin can be bypassed, if you click on the link provided in the monitor you can get more extended information.

timja allan_burdajewicz I replayed the use case and indeed the issue is visible only when the Audit Trail security monitor introduced in Audit Trail 3.7 is triggered. I debugged further, the frontend never sends a POST request to /jenkins/pipeline-syntax/generateSnippet. Upon looking further, the faulty call is around there:

https://github.com/jenkinsci/workflow-cps-plugin/blob/0e4c25f8d7b84470aa523491e29933db3b3df588/src/main/resources/org/jenkinsci/plugins/workflow/cps/Snippetizer/index.jelly#L83

Interestingly enough, there is a comment from jglick saying this call can fail in some circumstances. Not clear to me if we are in the same circumstances.

Right now I cannot understand the link because the failing js side, and this admin monitor: https://github.com/jenkinsci/audit-trail-plugin/blob/aeb49db71a1a4ec715286f93c42f581808f49592/src/main/java/hudson/plugins/audit_trail/BypassablePatternMonitor.java

The comment is referring to the outdated prototype javascript library we use and how it hijacks the javascript prototypes and breaks certain methods...