Quick Answer
The answer is an expired or misconfigured SAML signing certificate. When a user is repeatedly prompted for credentials and then receives an error during SAML-based SSO, the application is rejecting the security assertion because the certificate used by Microsoft Entra ID to sign it no longer matches what the application expects. This mismatch can stem from an expired certificate, an incorrect thumbprint, or a misaligned audience URI or reply URL in the Entra ID configuration. On the AZ-500 exam, this scenario tests your ability to diagnose federation failures, often appearing as a troubleshooting question where the trap is to blame user permissions or network issues instead of certificate lifecycle management. A key memory tip is to think of the SAML certificate as a digital handshake: if the handshake is expired or the grip is wrong, the application won’t let the user in, forcing repeated login loops.
This AZ-500 practice question tests your understanding of secure identity and access. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You are troubleshooting why a user cannot sign in to a custom line-of-business application that is federated with Microsoft Entra ID. The user reports that they are repeatedly prompted for credentials and then receive an error. The application is configured for SAML-based SSO. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The user's browser cookies are disabled
Why wrong: May cause issues but not the primary cause.
The application is not registered in the app gallery
Why wrong: Custom apps can be registered.
The SAML certificate has expired or the configuration has a mismatch
Common SAML SSO issue.
The user does not have a license for Microsoft Entra ID
Why wrong: Free tier supports SSO.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The SAML certificate has expired or the configuration has a mismatch
When a SAML-based SSO application repeatedly prompts for credentials and then fails, the most common cause is an expired or misconfigured SAML signing certificate. The certificate is used by Microsoft Entra ID to sign SAML assertions; if it has expired, or if the thumbprint, audience URI, or reply URL in the Entra ID configuration does not match what the application expects, the application will reject the assertion and force re-authentication or display an error.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The user's browser cookies are disabled
Why it's wrong here
May cause issues but not the primary cause.
The application is not registered in the app gallery
Why it's wrong here
Custom apps can be registered.
The SAML certificate has expired or the configuration has a mismatch
Why this is correct
Common SAML SSO issue.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
The user does not have a license for Microsoft Entra ID
Why it's wrong here
Free tier supports SSO.
Common exam traps
The trap here is that candidates often confuse a SAML certificate expiration/mismatch with a licensing issue or browser configuration problem, but the repeated credential prompt followed by an error is the hallmark of a failed SAML assertion validation, not a missing license or disabled cookies.
Detailed technical explanation
SAML 2.0 assertions are digitally signed using the private key corresponding to the certificate uploaded to the enterprise application in Entra ID. The relying party (the application) validates the signature using the public key from the metadata; if the certificate has expired, the signature verification fails, and the application returns a SAML error (e.g., 'Invalid signature' or 'Response not trusted'). In real-world scenarios, certificate rotation is often overlooked, and administrators must update the application's trust settings before the old certificate expires to avoid this exact failure.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
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Secure identity and access — study guide chapter
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FAQ
Secure identity and access — This question tests Secure identity and access — Read the scenario before looking for a memorised answer..
The correct answer is: The SAML certificate has expired or the configuration has a mismatch — When a SAML-based SSO application repeatedly prompts for credentials and then fails, the most common cause is an expired or misconfigured SAML signing certificate. The certificate is used by Microsoft Entra ID to sign SAML assertions; if it has expired, or if the thumbprint, audience URI, or reply URL in the Entra ID configuration does not match what the application expects, the application will reject the assertion and force re-authentication or display an error.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 25, 2026
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