Useful or not, from you.
matrix-appservice-irc registration config issue

I can receive messages from the matrix client riot into my IRC channel. When sending messages from IRC the bridge gets the following error:

{"errcode":"M_EXCLUSIVE","error":"Invalid user localpart for this application service. {"errcode":"M_FORBIDDEN","error":"Application service has not registered this user"}

I reviewed all parameters 2 days long... no success. Any idea?

That's a useful answer
Without any help

I get the same error when trying to join some channels (it works for others).

In particular, it does this:

INFO:IrcBridge [-] POST (AS) Body: "{\"auth\":{},\"username\":\"LOCALPART\"}" 

wher LOCALPART is the localpart of my matrix user requesting to join the channel. From my limited knowledge, it seems that the bridge want's to register this username. Why on earth would it try to do this? Surely, setting the regex to .* like in the above comment isn't the solution.