M_FORBIDDEN: "Can not create filter for other user"

[IngwiePhoenix]

Getting filter failed [M_FORBIDDEN: Cannot create filters for other users] {
  errcode: 'M_FORBIDDEN',
  name: 'M_FORBIDDEN',
  message: 'Cannot create filters for other users',
  data: {
    errcode: 'M_FORBIDDEN',
    error: 'Cannot create filters for other users'
  },
  httpStatus: 403
}

This is the error I get when trying to run the bridge. Configuration should be adequate as no other errors happened so far. Unfortunately, this is where I am stuck at :)

At least I thought so. I had a hunch: When Riot displayed my username in all lowercase, I realized I had logged in with IngwiePhoenix as my localpart - but I was supposed to lowercase it entirely.

So what actually happened: The bridge was trying to set filters for IngwiePhoenix, whilst being logged in as ingwiephoenix.

Might be useful to know for other bridges too, methinks!