401 Unauthorized: Access is denied due to invalid credentials

Solution 1:

I realize this is an older post but I had the same error on IIS 8.5. Hopefully this can help another experiencing the same issue (I didn't see my issue outlined in other questions with a similar title).

Everything seemed set up correctly with the Application Pool Identity, but I continued to receive the error. After much digging, there is a setting for the anonymous user to use the credentials of the application pool identity or a specific user. For whatever reason, mine was defaulted to a specific user. Altering the setting to the App Pool Identity fixed the issue for me.

1. IIS Manager → Sites → Website
2. Double click "Authentication"
3. Select Anonymous Authentication
4. From the Actions panel, select Edit
5. Select Application pool Identity and click ok

Hopefully this saves someone else some time!

Solution 2:

If you're using IIS 7 do something like this:

1. Select your site.
2. Click on error pages.
3. Edit feature settings.
4. Select detailed errors.

Solution 3:

Make sure that you enabled anonymous authentication on iis like this:

Solution 4:

In case anyone is still looking for this, this solved the problem for us:

To whoever this may help, this saved my life...

IIS 7 was difficult for figuring out why i was getting the 401 - Unauthorized: Access is denied due to invalid credentials... until i did this...

1. Open IIS and select the website that is causing the 401
2. Open the "Authentication" property under the "IIS" header
3. Click the "Windows Authentication" item and click "Providers"
4. For me the issue was that Negotiate was above NTLM. I assume that there was some kind of handshake going on behind the scenes, but i was never really authenticated. I moved the NTLM to the top most spot, and BAM that fixed it.

Here is the link where this was found.

Solution 5:

I realize its an old question, but this came up in my searches. Had a similar issue for an MVC application recently built, deployed for the first time, and Authentication mechanism wasn't completely hashed out.

It wasn't an IIS setting in my case, it was a Controller that was not [AllowAnonymous] decorated. I was using a Render.Action/Html.Action in a Layout.cshtml and the User was unauthenticated. So the Layout tried to load an Authenticated Action in an UnAuthenticated context.

Once I updated the action to AllowAnonymous, the problem went away, and this is what led me to it.

Hope this helps someone.