Azure Single Sign On (SSO) can streamline access across cloud and SaaS apps—but when it breaks, it breaks at scale. Whether users are getting unexpected sign in prompts, looping redirects, or mysterious “AADSTS” error codes, Azure SSO issues can disrupt productivity and erode trust quickly. For organizations relying on cloud engineering to power their infrastructure, a broken identity layer is one of the most impactful failures to address.
In this post, we’ll walk through common root causes, actionable steps for troubleshooting, and best practices to ensure your identity layer stays resilient.
First, Understand the Flow
Before jumping into logs, it helps to understand the basic Azure AD SSO handshake:
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User accesses an application (like Salesforce, Teams, or a custom app).
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The app redirects the user to Azure AD to authenticate.
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Azure AD validates the user via their credentials or existing session (e.g., Windows Integrated Auth or PRT).
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If successful, Azure AD issues a token and redirects the user back to the application.
If any one of these steps fails—due to misconfigurations, expired tokens, or conditional access policies—SSO breaks.
Common Symptoms and Root Causes
How to Troubleshoot Azure SSO Step-by-Step
1. Check Sign-in Logs
Start in the Azure AD Sign-in logs:
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Filter by user, app, and timestamp
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Look for AADSTS error codes like:
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AADSTS50020– User not in tenant -
AADSTS700016– App/client not found -
AADSTS50105– User blocked by Conditional Access
2. Review Enterprise App Settings
Navigate to Azure Active Directory → Enterprise Applications:
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Make sure SSO mode matches what the app expects (e.g., SAML vs OAuth2). Microsoft’s guide on debugging SAML-based SSO is a valuable reference here.
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Validate:
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Identifiers (Entity ID, App ID URI)
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Certificates (expiration and thumbprint match)
Apps like Workday or ServiceNow often require certificate updates every year. Microsoft’s guide on troubleshooting SAML-based SSO covers additional certificate and configuration issues.
3. Use the MyApps Test Tool
Have the user go to myapps.microsoft.com, click the app, and review the real-time authentication flow. This helps isolate whether the issue is user-specific, app-specific, or tenant-wide.
4. Validate Conditional Access
Conditional Access is a critical component of any security and compliance strategy. Check for policies in Azure AD → Security → Conditional Access that may:
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Block sign-in by location
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Require compliant or hybrid-joined devices
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Trigger unexpected MFA prompts
Tip: Use Report-only mode to test new policies before enforcing them. For more detail, see Microsoft’s documentation on troubleshooting Conditional Access sign-in problems.
5. Inspect Domain and User Settings
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Verify the user’s UPN matches the expected domain suffix (e.g., user@company.com)
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Check that the domain is verified and federated if needed
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For Hybrid setups, confirm Seamless SSO is enabled and GPOs are configured properly
Hybrid Azure AD Join & PRT Issues
In hybrid environments, SSO often relies on Primary Refresh Tokens (PRTs) issued when a device is Azure AD joined or hybrid joined. If devices aren’t joined correctly, or if the user signs into a local account, SSO won’t work. Proper device management is a key part of delivering modern workplace solutions that work reliably for end users.
Check device status via:
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dsregcmd /status on Windows
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Azure AD portal → Devices
A healthy device should show:
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AzureADJoined = YES
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PRT = YES
Best Practices to Prevent Future Issues
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Renew certificates proactively for SAML-based SSO apps
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Document app configs—including reply URLs, identifiers, and roles
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Monitor logs continuously using Azure Monitor or Sentinel
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Use groups for access control, not individual users
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Automate testing with tools like Microsoft Graph or Playwright if you manage many apps
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Partner with a provider offering managed IT services to handle ongoing monitoring and maintenance of your identity infrastructure
Frequently Asked Questions
Why is Azure SSO not working? Azure SSO can fail for a variety of reasons, including misconfigured reply URLs, expired SAML certificates, Conditional Access policies blocking sign-in, or device join issues in hybrid environments. The best first step is to check the Azure AD Sign-in logs for specific AADSTS error codes, which will point you toward the root cause.
How do I troubleshoot Azure Single Sign-On? Start by reviewing the sign-in logs in the Azure portal, filtering by the affected user and application. Look for AADSTS error codes, then validate your Enterprise App configuration (SSO mode, reply URLs, certificates). Test the authentication flow via myapps.microsoft.com and check Conditional Access policies for any rules that may be blocking access.
What is Azure AD SSO? Azure AD Single Sign-On (SSO) is a feature of Microsoft Entra ID (formerly Azure Active Directory) that allows users to sign in once and access multiple cloud and SaaS applications without re-entering their credentials. It supports protocols like SAML, OAuth 2.0, and OpenID Connect, and can be extended to on-premises apps through hybrid configurations.
How do I fix AADSTS error codes in Azure? AADSTS error codes are returned by Azure AD when authentication fails. Each code maps to a specific issue—for example, AADSTS50107 means MFA is missing, AADSTS700016 means the app or client ID was not found, and AADSTS50105 means the user is blocked by Conditional Access. Look up the specific code in Microsoft’s documentation, then address the underlying configuration or policy issue.
Need Help Managing Azure Identity?
Exodata specializes in designing, securing, and supporting enterprise identity environments on Microsoft Azure. Whether you’re integrating SSO for hundreds of SaaS apps or troubleshooting hybrid join problems across your fleet, our team can help ensure your users get seamless, secure access—every time. Contact us to discuss your Azure identity needs.