AdHoc: exception initializing ad hoc

[amayr]

I'm currently migrating from jasperserver 3.5 to 3.7.

Most things are working again, but I got a serious issue in ad hoc reporting. We keep getting an error, whenever we want to open an adhoc topic. See picture and textfile for details. The first few lines of the stack trace:

10:54:34,405 ERROR [AdhocAction] exception initializing ad hoc
com.jaspersoft.commons.datarator.exception.DataratorRetrievalException: java.lang.NullPointerException
        at com.jaspersoft.ji.adhoc.action.AdhocAction.setReportModelInContext(AdhocAction.java:1358)
        at com.jaspersoft.ji.adhoc.action.AdhocAction.view(AdhocAction.java:560)
        at com.jaspersoft.ji.adhoc.action.AdhocAction.initForTopic(AdhocAction.java:398)

Please ask if you need any more information.

We are using jasperserver-pro 3.7.0 and custom datasources. Changing setting in the adhoc-options does not seem to have any effect. I'm grateful for any help or some words of consolation. ;-)