Hi @Sanjeewa Aththanayaka • Thank you for sharing required details.
I tracked the correlation ID and found that the user is not present in your tenant, which is why you are getting this error. There are multiple ways to resolve this error.
1 Invite the user as guest user to your tenant. Once the users accept the invite they can access the application. For this purpose, navigate to:
Azure Active Directory > Users > +New Guest User > provide required details > Invite.
2 Create Self Service Sign-up by creating a user flow and adding your application to the user flow. Users can then use create account link to create their accounts by themselves. Read More: https://learn.microsoft.com/en-us/azure/active-directory/external-identities/self-service-sign-up-overview
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