What causes Azure AD B2C to throw a 500 error during Run User Flow?

dapug 1 Reputation point
2021-09-10T20:30:51.59+00:00

I created a new Azure AD B2C for an existing subscription to test out a basic hello-world auth scenario. And it fails with a 500 error using the portal's own tools.

-Create a new Azure AD B2C linked to an existing subscription
-Enable Sign In Sign Up User Flow (email/phone, local account)
-Register an app as SPA with https://jwt.ms as a redirect URI
-Run User Flow

Result is a 500 server error.

It will load the SUSI page BUT if I click on "Sign up with Phone signup or Email signup" it throws a 500.

So, this loads ok:
https://<mydomain>.b2clogin.com/<mydomain>.onmicrosoft.com/oauth2/v2.0/authorize?p=B2C_1_susi_phone_email&client_id=[guid]&nonce=defaultNonce&redirect_uri=https%3A%2F%2Fjwt.ms&scope=openid&response_type=code&prompt=login&code_challenge_method=S256&code_challenge=[blah]

Clicking sign-up redirects here and FAILS (500):
https://<mydomain>.b2clogin.com/<mydomain>.onmicrosoft.com/B2C_1_susi_phone_email/api/CombinedSigninAndSignup/unified?claimsexchange=SignUpWithLogonEmailExchange&csrf_token=[blah-big-token]==&tx=StateProperties=[blah-data]&p=B2C_1_susi_phone_email

Now, I could ask about what I configured wrong, but even if I did configure something wrong... the 500 error is NOT a response we should be getting from Azure using their own sanctioned built-in user flows for this. That is a Bug for sure - if something is wrong a proper error should be caught and returned.

NO error shows up in Audit Log. There is NO way to diagnose further, and its a SHOW STOPPER. I cannot proceed. So aside from a legit bug regarding the error, has anyone else experienced this, or know of things I should check?

Microsoft Entra External ID
Microsoft Entra External ID
A modern identity solution for securing access to customer, citizen and partner-facing apps and services. It is the converged platform of Azure AD External Identities B2B and B2C. Replaces Azure Active Directory External Identities.
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  1. James Hamil 21,391 Reputation points Microsoft Employee
    2021-09-14T21:48:24.327+00:00

    Hi @dapug , I recreated your steps and did not have any issues on my end. I assume you followed this tutorial series? My suggestion unfortunately is to delete what you have and try making it again. If you still get the same error then we'll need to open up a support ticket. Please let me know.

    Thank you,
    James