I upgraded to Jira 6.0.1 and have an issue with one of the validators in the tool box.
I attached a screen shot of the validator.
When it is run I get the following error messagae...
Error creating issue: An unknown exception occured executing Validator com.fca.jira.plugins.workflowToolbox.UserInFieldInRolValidator@115a05ee: root cause: com.atlassian.jira.user.DelegatingApplicationUser cannot be cast to com.atlassian.crowd.embedded.api.User
Screen shot also attached