rrd_fetch_json.php returns html when user is unauthorized (causes "Error: SyntaxError: Unexpected token <")
The rrd_fetch_json.php endpoint should always return json, as it normally is being requested by js or something that intends to parse it.
When the user's session expires (or if the user is unauthorized), this endpoint returns the html for the login page, causing the js that tries to parse it to error out.
1. Go to status monitoring
2. Wait for the session to expire (or log out in a separate tab)
3. Press reload on the graph
5. "Error: SyntaxError: Unexpected token <"
The endpoint should return some kind of json formatted error message, which the js can parse and either display an appropriate message or redirect the whole page to login.