I had multiple of these this season, seems like IRS decided to change the name control for lots of 1041 filers....I was able to get acceptance by using the first 4 letters of the last name in the trust name.   For example  my trust name was  TJ Jones Trust, so the EFname control TJJO has always worked in the past, this year I had to make the 4 digits be  JONE for it to get accepted.

I saw another preparer said they had to use the first 4 letters ofthe trustees last name to get it accepted (in all my situations the trustees last name was the same as the trust, so it could be the trustees last name that needs to be used), it may take you a few tries to get it right.