B2C issue - "Error detail - the application was not found"

Question

B2C issue - "Error detail - the application was not found"

RoryB 460

Part of the B2C to EEID migration is authenticating against B2C.

This uses ROPC.

As per the docs, I tried to create an ROPC app. registration in B2C, and I needed to add:

"oauth2AllowImplicitFlow": true,

to the manifest.

But I got:

Error

This will affect anyone trying to set up a migration?

I've tried this on two different B2C tenants.

Any ideas?

Carolyne-3676 1,116 Reputation points

2026-02-10T07:19:31.56+00:00

Hello Rory!
This error looks like a propagation issue. Did you retry and still get the same error?
Here are a couple of things to looks out for:
Please ensure the application is registered in Azure AD B2C tenant under "App Registrations" and verify that the Application (client) ID matches the one configured in your request.

In the App Manifest Configuration, check if "oauth2AllowImplicitFlow": true is enabled in the app manifest for implicit grant support. Navigate to Azure Portal > App Registration > Manifest, edit appropriately, and save. Lastly, please note that this flow is no longer recommended by Microsoft for the reasons detailed in this document particularly with matters related to MFA - https://learn.microsoft.com/en-us/entra/identity-platform/v2-oauth-ropc
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RoryB 460 Reputation points

2026-02-10T08:09:47.3233333+00:00

Hi @Carolyne-3676,

This is an issue with creating the app. registration, not with calling ROPC

"In the App Manifest Configuration, check if "oauth2AllowImplicitFlow": true is enabled in the app manifest for implicit grant support."

No, it is not enabled.

The problem is that it throws the above error when I try and add that attribute to the manifest!
Thanmayi Godithi 7,265 Reputation points Microsoft External Staff Moderator

2026-03-13T19:56:35.05+00:00

Hi @RoryB,

Did you try to use PowerShell to enable the oauth2AllowImplicitFlow in the application?