A user was unable to access the application because their account was not provisioned. The issue resolved on its own after the user successfully authenticated at a later time.

Investigation indicated elevated authentication errors and increased application exceptions during the affected period. Although the application remained available, authentication reliability was degraded, impacting some users attempting to sign in or be provisioned for the first time.

The issue was caused by a known limitation of the v1 application architecture, which uses in-memory storage for OIDC nonce values across multiple App Service instances.

During a process recycle, scaling operation, platform maintenance event, or similar infrastructure refresh, the in-memory nonce stores can be cleared. If a user's authentication transaction spans such an event, nonce validation may fail, resulting in authentication errors such as IDX21323.

For newly onboarded users, authentication must complete successfully before account provisioning can occur. When authentication fails, the provisioning workflow does not execute, leaving the user unable to access the application.

Because the application continues serving most requests during these events, users experience intermittent authentication failures rather than a complete service outage.

The issue typically resolves once the user successfully completes authentication after the environment stabilizes.

Immediate resolution:

• Have the affected user retry authentication after a short period.
• Confirm that authentication succeeds and that the provisioning process completes.
• Verify that the user's account has been created and can access the application.

Long-term resolution:

• Migrate to the v2 architecture, which removes the dependency on in-memory nonce storage and eliminates this class of authentication-related provisioning failures.
• Continue monitoring for elevated OIDC nonce validation errors (IDX21323) as indicators of application instance recycles or similar infrastructure events.