We were receiving the same error when opening Lacerte or doing anything that triggered communication with Lacerte.  There were no returns stuck in the queue, but we were not receiving any efile updates. 

I renamed the  ...\19TAX\OPTION19\EF to \LACERTE\19TAX\OPTION19\EFold (according to the instructions noted earlier) and the error stopped popping up and we suddenly received a wave of efile updates, so it appears to be fixed.