How to check the WWW-Authenticate Header Response

At this point, if the issue hasn’t been fixed, it may be caused by a server-side problem. This means our last fix will be a bit more involved.
As we saw earlier, the 401 response is sent through the WWW-Authenticate header, which appears as “WWW-Authenticate: <type> realm=<realm>”. It includes ‘challenges’, or strings of data that indicate what type of authentication is required in order for access to be granted.
In a nutshell, you’ll want to check and see if the header response was sent, and more specifically, what authentication scheme was used. At the very least, this can help narrow down the cause of the problem, and bring you one step closer to a solution.
To do this, go to the web page that’s displaying the 401 error, and access the developer console in Chrome. You can right-click on the page and select Inspect, or use Ctrl+Shift+J.
Next, click on the Network tab and reload the page. This will generate a list of resources. Select the Status header to sort the table and locate the 401 status code:

Select that entry, and then click on the Headers tab. Under Response Headers, locate the WWW-Authenticate header:

The information that is present in the response header, particularly the authentication schemes, can give you more information about what’s happening and point you towards a solution. It can help you understand what type of authentication the server is expecting.
For example, in the above example, we can see that the authentication scheme is “Basic”. This means the authentication request should only require an ID and password. For more detailed information and instructions on how to use this information, we recommend referring to the HTTP Authentication Scheme Registry.