If a server reaches its MAU, it is no longer able to create appservice users.

[Half-Shot]

Note, bridge users do not count against MAU. However if your homeserver reaches the MAU limit with real users and then an appservice tries to register ghost users, it will fail with "errcode":"M_RESOURCE_LIMIT_EXCEEDED","error":"Monthly Active User Limit Exceeded"

This may also be the case for other custom user types too.

[rxl881]

@danc86 -- Is there any chance that we would be able to get a hot-fix for this relatively quickly?

[Half-Shot]

Offending registration check:

synapse/synapse/handlers/register.py

Lines 208 to 210 in f14428b

	# do not check_auth_blocking if the call is coming through the Admin API
	if not by_admin:
	await self.auth.check_auth_blocking(threepid=threepid)

More generally

synapse/synapse/api/auth_blocking.py

Line 40 in f737368

async def check_auth_blocking(

should probably not block actions from appservice users.

[callahad]

With apologies to @danc86 -- I'm @callahad, he's someone else :)

[rxl881]

Whoops!! Sorry for the erroneous mention, I'm going to blame a combination of lack of coffee and over-dependence on auto-complete :( (thanks for catching that "the real" @callahad)