This can occasionally happen if the WER database is not in a state that the program is happy with, or if something in the startup process of WER couldn't do what it thought it should be able to do. (which restarting WER again can sometimes help with)
You can contact your WPN representative in these instances, or log a ticket in the WotC Customer Service portal and they will likely have further recommendations on making sure that this does not happen as frequently in the future.