Why does my site redirect back to the Login screen

Question

I'm upgrading an ASP.Net MVC4 site to MVC5, and implementing the new OWIN Authentication methods in the process.

I've copied over the action methods from the Account controller on a blank MVC5 project.

The problem is, when I click an external provider button (e.g. Google) I just get redirected back to the login page again. The second time I click it, I do get taken to the Google account page, but then the browser gets redirected to the Account/External login page.

What's going on?

Answer 1

Check the <authentication> element in your web.config file. It is probably still saying

<authentication mode="Forms">

Changing it to <authentication mode="None"> should fix the problem.

For good measure, remove the FormsAuthentication module from your webserver modules section:

<system.webServer>
  <modules>
     <remove name="FormsAuthentication" />
   </modules>
</system.webServer>

The problem is that the FormsAuthentication module looks out for any responses with a 401 (Unauthorised) code and changes them into a redirect request to your login page.

Answer 2

I had the same issue and Samuel Jack's answer did help me, but I had to make a slight change.

For me, adding the

<remove name="FormsAuthentication" /> 

under the "handlers" section did not work. Instead, I had to add it under the "modules" section as below and the issue was resolved.

Here is how my web.config looks.

  <system.webServer>
    <modules>
      <remove name="FormsAuthentication" />
      <remove name="FormsAuthenticationModule" />
      <remove name="RoleManager" />
    </modules>

Note that in my case, there already was a

<remove name="FormsAuthenticationModule" />

in my web.config but that did not help solve the issue. I don't know how it got there so I left it alone.

Hope this helps.

Answer 3

I had this exact problem for 1 day straight, but sometimes I have some bad days and my attention to details is low.

But my problem was a bit awkward. My external logins were fine for like few months and suddenly stopped working and I didn't touched that code at all however my webconfig was...

 <location path="something/somethingelse">
     //other stuff that made it hard to see because is pretty long
   <system.webServer>
      <modules>
         <remove name="FormsAuthenticationModule" />
         <remove name="FormsAuthentication" />
      </modules>
   </system.webServer>
 </location>

Luckily I figured this out before posting a question I was about to write and made me see that location tag.

I have no idea why it worked in the first place then got broken later. I haven't updated any reference, did literally nothing to this for weeks.