How to troubleshoot Conditional Access sign-in failures

Step by step to find the reason your CA rules are blocking access

1/1/20262 min read

How to troubleshoot Conditional Access sign-in failures using Entra ID logs

Ok, so you got some sign in failures, and you need to find out what the issue is and where you can start troubleshooting. This is a "How to troubleshoot Conditional Access" guide .

What this guide covers

  • Where to find exactly which Conditional Access policy caused a sign-in failure

  • How to interpret Entra ID sign-in logs step by step

  • How to fix the most common Conditional Access misconfigurations

Step 1: Open the correct sign-in logs (this matters)

Not all logs show Conditional Access decisions.

  1. Go to Microsoft Entra ID

  2. Navigate to Monitoring → Sign-in logs

  3. Click the failed sign-in you want to analyze

  4. Select the Conditional Access tab inside the log entry

This view is the only place where policy evaluation results are shown.

Step 2: Identify the policy that blocked the sign-in

Inside the Conditional Access tab, look for:

  • Result: Failure

  • Policy name: The exact CA policy responsible

  • Grant controls: What requirement was not met

    (MFA, compliant device, approved client app, etc.)

If multiple policies apply, any single failure blocks the sign-in.

Step 3: Check the “Report-only” section (often overlooked)

Even if a policy is not enforced, it can still appear in the logs.

  1. Scroll to Report-only policies

  2. Review policies marked as:

    • Would have failed

    • Would have succeeded

This is critical when:

  • Testing new policies

  • Troubleshooting unexpected future failures

  • Validating changes before enforcement

Step 4: Validate conditions that caused the failure

Expand the failed policy and verify each condition:

  • User or group assignment

  • Cloud app

  • Client app type

  • Device platform

  • Sign-in risk

  • Device compliance state

Common example:

A policy requires a compliant device, but the device has not yet checked in with Intune—or failed compliance.

Step 5: Fix the issue without weakening security

Once you identify the cause, apply the smallest possible fix:

  • Trigger Intune compliance sync on the device

  • Adjust policy scope (exclude specific apps, not users)

  • Convert broad exclusions into narrow conditions

  • Move high-risk rules to privileged roles only

Avoid disabling the policy unless absolutely necessary

Common mistake: Looking only at “Sign-in blocked”

Why this fails:

  • The error does not tell you which policy failed

  • It hides competing policies

  • It ignores report-only evaluations

Always drill into the Conditional Access tab.

Summary

  • Use Entra ID sign-in logs to see the exact blocking policy

  • Review both enforced and report-only Conditional Access results

  • Fix failures by adjusting conditions, not disabling policies

Go 4 it ! 😀