I had Timeshift open while doing an update via Pamac and received failed to run transaction hooks
Looked in the logs and realized why:
Creating Timeshift snapshot before upgrade...
Another instance of this application is running (PID=6114)
Unable to run timeshift-autosnap! Please close Timeshift and try again. Script will now exit...
Error: command failed to execute correctly
Failed to commit transaction:
failed to run transaction hooks
Closed Timeshift and the update went with out a hitch.
Anyway, thought Iād post in case someone got the error and started Googling.