Evan “Doc” Watson sends a tip to remember to clear out old/unused reports prior to upgrading to CRM 2013/2015. The dependency check in the upgrade process will kill your upgrade if any entities referenced in a report no longer exist in the environment.

If you have any reports that reference an entity that has been removed, you will see an error in the upgrade log that looks something like this:

Should this happen to you, you will need to delete the report (if you can), or if it won’t let you delete the report, recreate the missing entity.