Introduction

In early January 2025, IT administrators encountered a critical issue: Microsoft Outlook 365 and other Microsoft 365 applications began crashing unexpectedly on Windows Server 2016 environments. This disruption significantly impacted organizations relying on these platforms for daily operations.

Background

The problem emerged after users updated their Microsoft 365 applications to Version 2412 (Build 18324.20168). Post-update, applications like Outlook, Word, Excel, and PowerPoint would crash within seconds of launching. The root cause was identified as the integration of the React Native framework in the recent Office update, which introduced compatibility issues with Windows Server 2016. (bleepingcomputer.com)

Technical Details

The crashes were linked to faults in the INLINECODE0 module, a core Windows library. Event Viewer logs displayed errors such as:

CODEBLOCK0

These errors indicated that the recent Office update's integration with React Native was incompatible with certain Windows Server configurations. (support.microsoft.com)

Microsoft's Response

Microsoft acknowledged the issue and released an update (Version 2412, Build 18324.20194) on January 16, 2025, to address the crashes. For systems configured to automatically update from the Office Content Delivery Network (CDN), no action was required. Administrators managing updates manually were advised to download and deploy the latest update. (bleepingcomputer.com)

Workaround Solutions

For those unable to apply the update immediately, Microsoft provided a workaround to revert to the previous stable version:

  1. Open Command Prompt with administrative privileges.
  2. Execute the following commands:

``INLINECODE1 ``

  1. To prevent automatic re-updating, disable updates by navigating to File > Office Account > Update Options > Disable Updates.
  2. Set a reminder to re-enable updates after February 11, 2025. (support.microsoft.com)

Implications and Impact

This incident underscores the challenges of maintaining compatibility between evolving software applications and legacy server environments. Organizations relying on Windows Server 2016 faced operational disruptions, highlighting the importance of thorough testing and phased rollouts of updates.

Recommendations

  • Monitor Updates: Regularly review and test software updates in a controlled environment before widespread deployment.
  • Backup Systems: Maintain up-to-date backups to mitigate the impact of unforeseen issues.
  • Stay Informed: Subscribe to official Microsoft channels for timely information on updates and known issues.

Conclusion

The Outlook 365 crashes on Windows Server 2016 serve as a reminder of the complexities involved in software updates within enterprise environments. By implementing proactive monitoring and testing strategies, organizations can better navigate such challenges and ensure continuity in their operations.