Microsoft documents one confirmed crash that happens when you open certain emails. Classic Outlook 2024 LTSC and Outlook 2021 LTSC crash on emails from Viva Engage, Viva Insights, Yammer and Power Automate. Windows logs Event 1000 with exception code 0xc0000005. Microsoft marks the issue as fixed in two stages and lists the build numbers. Outlook 2016 does not appear in the article.
Outlook closes the moment you open one particular message. Other messages open normally. This pattern is the one Microsoft documents in a known issue article.
Facts follow the Microsoft Support known issue Outlook LTSC crashes opening Viva Engage emails. Microsoft last updated it on May 1, 2026.
Which Outlook Versions Crash?
Microsoft names classic Outlook 2024 LTSC and classic Outlook 2021 LTSC. Outlook 2016, Outlook 2019 and Microsoft 365 Apps do not appear in the article.
What are the Symptoms?
- Crash on open. Classic Outlook closes when you open an email sent from Viva Engage, Viva Insights, Yammer or Power Automate.
- Event Viewer entry. Windows logs Event 1000 for OUTLOOK.EXE with exception code 0xc0000005. Microsoft describes this code as an access violation.
What are the Microsoft Fix Builds?
| Product | First fix (March 10, 2026 update) | Second fix (expected May 12, 2026 update) |
|---|---|---|
| Outlook 2021 LTSC | Build 14334.20560 | Build 14334.20662 |
| Outlook 2024 LTSC | Build 17932.20694 | Build 17932.20766 |
Microsoft marks the status as fixed. Microsoft says the second and final set of fixes is still to come. Microsoft does not confirm that release as completed.
Crash logs in the article cite Outlook 2021 build 14334.20440 and Outlook 2024 builds 17932.20620 and 17932.20700. These builds crash.
What does Microsoft Not Say?
- Root cause for the crash.
- Workaround before you install the fix build.
- Any crash cause for Outlook 2016, Outlook 2019 or other versions.
Outlook sometimes freezes instead of closing. Microsoft documents that case separately. See how to fix Outlook that is not responding. Related reading also includes Outlook 2019 will not open.
Frequently Asked Questions
Why does Outlook Crash When I Open Certain Emails?
Microsoft documents one confirmed case. Classic Outlook 2024 LTSC and 2021 LTSC crash on emails from four Microsoft services.
Does This Crash Affect Outlook 2016?
Microsoft does not say. Only Outlook 2024 LTSC and Outlook 2021 LTSC appear in the article.
How do I Confirm the Crash in Windows?
Open Event Viewer and look for Event 1000 on OUTLOOK.EXE with exception code 0xc0000005. This is the signature Microsoft describes.
Which Build Fixes the Crash?
Microsoft lists 14334.20560 and 17932.20694 as first fixes. It lists 14334.20662 and 17932.20766 as the second and final fixes.
Is There a Workaround?
Microsoft does not list one in the article.
Key Takeaways
- Microsoft documents the crash for two LTSC editions of classic Outlook.
- Emails from Viva Engage, Viva Insights, Yammer and Power Automate trigger it.
- Event 1000 with code 0xc0000005 is the Windows log signature.
- Microsoft lists fix builds in two stages and gives no workaround.
- Outlook 2016 does not appear in the Microsoft article.
Sources and References
Facts follow Microsoft Support.
- Outlook LTSC crashes opening Viva Engage emails (Microsoft Support known issue) support.microsoft.com