Http Error: 401 Unauthorized

401 Unauthorized

The 401 http status code is returned when a request is made to a resource that requires authentication, but the credentials are not provided. This can happen for a number of reasons, but the most common cause is simply forgetting to include the necessary authentication information in the request. 

If you receive a 401 status code when making a request, it is important to first check that you are including the correct authentication information.

Example:

A user will receive a 401 status code when accessing a protected resource until they provide a valid username and password (or in some cases a bearer token).

See the below  links for configuring HTTP authentication in popular web servers:

RFC #: 7235 section 3.1