A revision was created, update and then accepted on Differential. After landing, the deamons refuse to close the revision due to the exception in P1109.
This doesn't kill the daemons but it does stop the import process for the branch with the offending commit.
The proper fix for this is T4045.
This shouldn't stop branch import for the entire branch, it should just stall that commit out. Are you definitely seeing the whole branch stop?
A (not very good) workaround is to cancel this task in /daemon/. That will stop it from retrying and failing over and over again, at the cost of not finishing the import. After the issue is fixed, you can reparse it with scripts/repository/reparse.php.