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Introduction
In this blog post, we’ll explore common causes of onboarding failures and sensor issues in Microsoft Defender for Endpoint (MDE). We’ll provide practical solutions to help you overcome these challenges.
Common Onboarding Failure Causes
Some of the most common reasons for MDE onboarding failures include network issues, policy conflicts, and remnants of third-party antivirus (AV) software.
Analyzing SENSE Event Logs
The SENSE event log at Applications and Services Logs > Microsoft > Windows > SENSE > Operational can help you diagnose sensor errors. By inspecting this log, you can identify potential issues with the MDE sensor.
MDE Client Analyzer Tool
The MDE Client Analyzer tool is a valuable resource for generating a comprehensive diagnostic report covering connectivity, sensor health, and policy delivery.
Sensor Health States
MDE sensors can be in three states: Active, NoSensorData, or ImpairedCommunication. Each state indicates a different issue that needs to be addressed.
Required Defender Service URLs and Proxy Configuration
Ensure the device can reach required URLs such as winatp-gw-*.microsoft.com and *.events.data.microsoft.com. If a proxy is in use, configure it correctly for MDE.
Disabling SSL Inspection
If your network has SSL inspection enabled, it may cause issues with MDE. Disable SSL inspection for Defender endpoints to improve connectivity.
Addressing Passive Mode Issues
For devices stuck in passive mode after third-party AV removal, set HKLM\SOFTWARE\Policies\Microsoft\Windows Advanced Threat Protection\ForceDefenderPassiveMode to 0 and reboot.
Conclusion
By understanding common onboarding failure causes, analyzing SENSE event logs, using the MDE Client Analyzer tool, and following these best practices, you can effectively address issues with Microsoft Defender for Endpoint onboarding and sensor errors.
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Written by Mohammed Akhter
Founder of ITP Training. 50,000+ students trained across 30+ countries in Microsoft endpoint and cloud security. Learn more →