This post doesn’t contain a tip, I’m asking the q and I don’t know the answer yet. Could just be a logic error on my part, in which case it was just a personal mystery and I thank you for helping!

MySQL error 1449 “There is no ‘username’@'host’ registered”

You can get a replication fail with this error if you have triggers, views or stored routines that run as their creator (which is usual) but the slave does not have that user. So far so good.

We just encountered a replication fail on multiple slaves (i.e. not a single isolated mishap) with this error on an UPDATE statement accessing a single base table (i.e. no view), and no triggers defined or routines called in the query. Indeed the slave did not have the reported user (intentionally), but that shouldn’t have mattered. Creating the user allowed replication to continue successfully – that’s no surprise either.

The question …