Intermittent ASP.NET oAuth issue with Google, AuthenticationManager.GetExternalIdentityAsync is returning null

Question

I am trying to fix an intermittent issue when using Google as an external login provider.

When attempting to login, the user is redirected back to the login page ra

Answer 1

I got this problem yesterday and I was COMPLETELY STUCK ! And, as you described, I got it just like that with no reason.

I managed to fix it (after hours of comparing 2 projects - 1 test project that worked no problem every time and another that was a more serious project - and they had the exact same code, but different dll versions)

The problem was with the DLLs - the referenced packages from Nuget. Make sure you have the latest packages and also check the runtime section in your web.config.

After I updated all Owin related packages and Microsoft.Owin and added:

... it worked again ! They might vary based on your used packages, but that's how it worked for me.