Which usernames? Just to clarify, it isn’t dependant on the names I try to request, but on which user (clientside) tries to perform the request. So it must be something related to the IP/connection/router/PC of that person that somehow makes the request invalid or that Twitch doesn’t like. And it’s only that endpoint, other endpoints work fine for the same person. If a username of that person is what you want I can try to get it.