---
title: Windows Authentication Prompt After Azure/Entra OAuth Login
slug: windows-authentication-prompt-after-azureentra-oauth-login
createdAt: 2025-08-15T02:30:46.769Z
---

## Symptoms

After logging in with **Azure/Entra OAuth** and being redirected, the user is unexpectedly challenged for **Windows Authentication**.

## Cause

This issue can occur when the **serverPrincipalName (SPN)** has not been registered against the **Active Directory server computer object**. Without the SPN, Kerberos authentication cannot complete, and the client falls back to prompting for credentials.

## Quick Diagnostic

Run the following command from an elevated Command Prompt or PowerShell session to check if the SPN is registered for the server:

:::BlockQuote
setspn -Q HTTP/\<serverFQDN>
:::

- Replace \<serverFQDN> with the fully qualified domain name of your server (e.g., myserver.domain.local).
- If no results are returned, the SPN is missing.

## Resolution

1. **Check SPN Registration**
   - Confirm the SPN for the server is registered in Active Directory using the diagnostic above.
2. **Register the SPN if Missing**
   - \<serverFQDN> – Fully qualified domain name of the server\<ServerComputerObjectName> – Name of the server’s computer object in Active Directory
   - Detailed instructions are available in our guide:
     &#x20;How to Configure SPNs
3. **Retry the Login**
   - After registering the SPN, retry the Azure/Entra OAuth login process.
   - The Windows Authentication prompt should no longer appear.