Oauth error

[chlsmith]

I'm getting the attached error after I have everything configured. I've had two sets of eyes examine my configuration on both the Azure and the TeamCity ends, and everything appears correct to me. On the AD side, I have users configured for access, but I don't even get to the point of putting in credentials after I configure the TeamCity end.

[RonnieHegelund]

It seems like it is requesting to authorize through it's own domain, instead of using https://login.microsoftonline.com

[davidshorter]

We had this same issue, our setup is TC with SSL behind URL re-write rule / reverse proxy using IIS.
IIS URL rewrite was interfering with it. After following the instructions here we were able to use AD Auth.

Seems to not be isolated to just Azure AD but any oauth2 flows.

[dtretyakov]

After the click on Log in using Azure Active Directory this plugin redirects to the Azure AD OAuth2 authorization page: https://login.microsoftonline.com/...

And if you have reverse proxy behind TeamCity which does not check server host while rewriting URLs Azure AD OAuth URL will be affected by URl rewrite.

So in such case please inspect reverse proxy rules.