We get error when we try to copy an existing job that has IvyTrigger configuration, and press save after performing build configuration (ie. changes to SVN URL, Build Section, etc) changes. Same behavior is observed when the source job (or the job being copied) is either a Free Style Project or Ivy Project.

<Error Stack trace> - refer to attachment ErrorStackTrace for complete stack trace of this
Status Code: 500
Exception:
Stacktrace:

java.lang.NullPointerException
at org.jenkinsci.plugins.ivytrigger.IvyTrigger.getContext(IvyTrigger.java:90)
at org.jenkinsci.plugins.ivytrigger.IvyTrigger.getContext(IvyTrigger.java:30)
at org.jenkinsci.lib.xtrigger.AbstractTriggerByFullContext.start(AbstractTriggerByFullContext.java:31)
at org.jenkinsci.lib.xtrigger.AbstractTrigger.start(AbstractTrigger.java:78)
at org.jenkinsci.lib.xtrigger.AbstractTrigger.start(AbstractTrigger.java:26)

Work around what we have found is:
1. Disable Ivy trigger plugin in the source job (ie. existing job)
2. Copy the job (ie. while creating a new job using Copy Job functionality on Jenkins UI)
3. Update all configurations and press Save.
4. Update Ivy trigger configuration in the new job and press Save.
5. Enable Ivy trigger configuration on the Source job and press Save.

If you have any queries, please email me at soumen.trivedi@gmail.com

Thanks & Regards
Soumen Trivedi