Problem started this week after we upgraded Jenkins (1.511 -> 1.514) and JobConfigHistory (2.3 -> 2.4).

On a job page, e.g. https://jenkins.mydomain.se/myProject/job/myJob/ when I Press the badge for "Config changed since last build" I get the error message:

"Job Configuration Difference
No permission to view config history"

In addition to that I get logged out from Jenkins.

In the logs I can see:

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Sep 23, 2013 2:24:40 PM hudson.ExpressionFactory2$JexlExpression evaluate
WARNING: Caught exception evaluating: it.getLines() in /3gsim/view/CSI%20Wall1/job/LSV%20status/jobConfigHistory/showDiffFiles. Reason: java.lang.IllegalArgumentException: Unable to get history from: null
java.lang.IllegalArgumentException: Unable to get history from: null
at hudson.plugins.jobConfigHistory.JobConfigHistoryProjectAction.getOldConfigXml(JobConfigHistoryProjectAction.java:198)
at hudson.plugins.jobConfigHistory.JobConfigHistoryProjectAction.getLines(JobConfigHistoryProjectAction.java:162)
at sun.reflect.GeneratedMethodAccessor975.invoke(Unknown Source)

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If I instead go to the Job Configuration History page, e.g. https://jenkins.mydomain.se/myProject/job/myJob/jobConfigHistory

and select the two latest versions there I have no problems getting the diff.

The links used on these two pages are almost identical. On the Job config History page it uses https, from the job page it uses http.