Last Updated: June 26, 2026
ISSUE
The Outlook Team’s telemetry is detecting a crash with Kaspersky antivirus module mcou.dll. If you are experiencing a crash and you use Kaspersky antivirus, use the steps below to confirm the crash.
Right click the Windows Start button and select Event Viewer.
In the Event Viewer window select Windows Logs, then Application Log.
In the Application log look for the time of your last Outlook crash and select the corresponding Event 1000 event.
In the Event 1000 event confirm if you see the Faulting application as Outlook.exe and Faulting module as mcou.dll like below.
Faulting application name: OUTLOOK.EXE, version: 16.0.19127.20302
Faulting module name: MCOU.DLL, version: 21.25.7.504
The crash occurs in following builds and percentages:
| Module | Build | Percentage |
|---|---|---|
| Mcou.dll | 21.25.7.504 | 92% |
| Mcou.dll | 21.24.8.1045 | 0.5% |
| Mcou.dll | 21.25.7.1025 | 0.1% |
STATUS: INVESTIGATING
If you are experiencing this crash, please contact Kaspersky support.
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See Also
Fixes or workarounds for recent issues in classic Outlook for Windows