As the error is clear and tells us that some of HTTP methods should be explicitly bound to action like “Get, Post, Delete or Put” so these steps should be check :
- Make sure all of the controller’s methods are surrounded by [HttpGet] and etcetera
- If your controller class inherited from a custom base class, check if all public methods of base class also surrounded by HTTP attributes like [HTTPGET], [HTTPPOST] or are protected (It was mine problem that my base class methods doesn’t has HTTP attribute)