Crash when user moves an issue in the TaskBoard - WARN [velocity] org.apache.velocity.runtime.exception.ReferenceException: reference : template = templates/greenhopper/jira/boards/planningboard/box/main.vm [line 33,column 168] : ${dropBoard.id} is not a

The user tried to move an issue in the taskboard, the loading froze and when he refreshed the page the instance was down. The reboot sometimes does the trick to fix it but the problem eventually comes back.

This is the last warnings we got in the logs before the instance crashed.

WARN [velocity] org.apache.velocity.runtime.exception.ReferenceException: reference : template = templates/greenhopper/jira/boards/planningboard/box/main.vm [line 33,column 168] : ${dropBoard.id} is not a valid reference.

WARN [velocity] org.apache.velocity.runtime.exception.ReferenceException: reference : template = templates/greenhopper/jira/boards/chartboard/dates.vm [line 2,column 33] : $selectedBoard.startDate is not a valid reference.