Reports not printable

Choose a report from the project page, e.g. "Timetracking Report". Then click the little printer symbol in the upper right corner of the web interface (decorator=printable).

This will result in

[ERROR] ServletDispatcher - -Could not execute action <java.lang.IllegalArgumentException: Invalid complete key specified: null>java.lang.IllegalArgumentException: Invalid complete key specified: null

at com.atlassian.plugin.ModuleCompleteKey.<init>(ModuleCompleteKey.java:17)
at com.atlassian.plugin.DefaultPluginManager.getEnabledPluginModule(DefaultPluginManager.jav
a:100)

Maybe for reports you need to use GET instead of POST?