Authentication servers down?

So I have two bot applications; one for testing and one in use. The one in use suddenly stopped working + it cannot start anymore. On startup, I receive error 401 (unauthorized). Now the curious thing is that my bot for testing purposes receives a 400 bad request. They have identical code but different secrets and IDs of course. Is something wrong with the servers or did i just miss something? I did not change my code for a while now, yet it stopped working now.

Just in case: I’m using this request

POST https://id.twitch.tv/oauth2/token
    ?grant_type=refresh_token
    &refresh_token=<refresh_token>
    &client_id=<client_ID>
    &client_secret=<client_secret>

And my code for it is this

axios({
	url: 'https://id.twitch.tv/oauth2/token?grant_type=refresh_token',
	params: {
		refresh_token: refreshtoken,
		client_id: clientID,
		client_secret: clientSecret,
	},
	method: 'POST',
	responseType: 'json'
})
.then(response => {
	if(typeof response === 'undefined'){
		console.log("!!! ERROR: Response undefined! Probably lost connection. Waiting...");
		return;
	}

	//printResponseData(response);
	let body = response.data;
	if(body)
		callback(body["access_token"], body["refresh_token"]);
	else
		console.log("Could not refresh token.");
})
.catch(err => {
	if(err) console.log(err);
})
.finally(() => {});

Sounds like your refresh token is no longer valid.

So you’ll have to obtain a brand new token/refresh token pair manually.

You should also read the body message of a response for further information.
The HTTP Code is only “half” the information.
The body will have further information