azure b2c custom policy responds with invalid username and password when it was working previously. HResult": "80131500

Joe W 0 Reputation points
2025-12-12T11:02:06.8966667+00:00

I have a B2C tenant with an app that is used to authenticate a SPA. This was working fine for the last year or so, but is now showing Invalid Username and Password when users try to login. The app registration debug SSO is showing that authentication was successful, but the trace log in app insights is showing Invalid Username and Password with the error code 80131500.

What's changed and what can I do to fix it?

Microsoft Security | Microsoft Entra | Microsoft Entra ID
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