Microsoft identifies Outlook bug: Here’s how to fix it today

Microsoft has announced a temporary fix for a known issue causing classic Outlook to crash when writing, replying to, or forwarding an email. This problem emerged after updating Outlook for Microsoft 365, Outlook 2021, Outlook 2019, or Outlook 2016 to Version 2412 (Build 18324.20168), released on January 7, which triggers “0xc0000005” exception codes.

Microsoft announces temporary fix for classic Outlook crashes

To verify if the crashing issue affects your Outlook, Microsoft advises checking the Windows Event Viewer Application Log for crash Event 1000 or Event 1001, alongside specific event details outlined in a recently published support document.

The Outlook team has identified a fix for this bug, planned for rollout to customers in the Current Channel on January 28, with Version 2501 Build 18429.20000. In the interim, affected users can revert Outlook to version 2411 (Build 18227.20162), which is not impacted by the crash issue.

To revert to the earlier version, users should search for ‘Command Prompt’ in the Windows search box, right-click the ‘Command Prompt’ icon, and select ‘Run as administrator.’ They then need to enter the following commands in the Command Prompt:

cd %programfiles%\Common Files\Microsoft Shared\ClickToRun
officec2rclient.exe /update user updatetoversion=16.0.18227.20162

Last week, Microsoft also released a fix for another issue causing Microsoft 365 applications and classic Outlook to crash on Windows Server 2016 or Windows Server 2019 systems. Earlier in January, it announced plans to automatically install the new Outlook email client on Windows 10 systems, starting with the February 2025 security update. In recent months, Microsoft provided temporary fixes for additional known Outlook problems, including one that led to crashes after opening and another affecting Gmail sign-in for classic Outlook users.

Featured image credit: Microsoft