Outlook - Endless Crashing for Several End-users

Question

Hello all,

We've been grappling with a problem for a few weeks and several solutions have been attempted.

The issue:

Outlook is crashing over and over again (9 times in one day for a single user yesterday), simply rebooting with no prompt or error message. This issue afflicts 5 end-users.

The solutions attempted:

Turn Com add-ins off

Repair office (offline, then online)

Office reinstall

Ran an "Outlook won't start" app that Microsoft recommends (step 3 in the link below)

Created new Outlook profile

Set cached exchange mode to only sync 3 days worth of data

Turned cached exchange mode off

Turned hardware acceleration off

Ran the SARA diagnostic tool and collected logs

Every solution listed in this list has been attempted:

https://learn.microsoft.com/en-us/exchange/troubleshoot/outlook-issues/crash-issues

The Environment:

Windows 10 Enterprise

End-users are RDPing into workstation VMs in Azure, using Outlook from there.

End-users are all using browser-based Dynamics

O365

Afflicted users have a shared mailbox along with their personal (some users have access to this shared box, but aren't crashing)

The Event Viewer log shows the Outlook crash:

Faulting application name: OUTLOOK.EXE, version: 16.0.13426.20332, time stamp: 0x5fcdcab3
Faulting module name: ucrtbase.dll, version: 10.0.19041.546, time stamp: 0x43cbc11d
Exception code: 0xc0000409
Fault offset: 0x000000000007287e
Faulting process id: 0x37fc
Faulting application start time: 0x01d6d7b7e2e9655b
Faulting application path: C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE
Faulting module path: C:\windows\System32\ucrtbase.dll
Report Id: 961a3d1d-0a33-499a-86d4-2339c0e02df6
Faulting package full name:
Faulting package-relative application ID:

Since the "faulting module path" pointed to a dll in System32, I also ran an sfc /scannow from a clients PC. This didn't alleviate the problem.

I have more detailed crash logs as well as CBS logs from the sfc /scannow if that would prove helpful.

Any assistance or advice would be greatly appreciated.

Thanks!

Answer 1

I see that you are using the Current Channel. An update for that Channel was released yesterday; Can you update and try it again?

Also try switching between Channels (Enterprise and Semi-Annual) and see whether the issue still reproduces.

Considering you are using an Enterprise environment, you could open a Premier Support Case as well. They can perform dumps and traces with you which can only be analyzed thoroughly by Microsoft Support Engineers.

Answer 2

Hi @Jordan Alway ,

Does the crash occur randomly or it can be triggered by any specific steps?
Have you tried adding one of the problematic user's account to a normal user's machine and see if the issue persists?

I am currently running the same version of Outlook and the version of the ucrtbase.dll is also exactly the same as yours, but so far I haven't experienced any Outlook crash issue. So it seems to me that it may be irrelevant to the Outlook version.

However, considering that the issue afflicts 5 particular end-users, I'd still recommend comparing both the detailed build number of Outlook and Windows OS with those on the normal users' machines to see if there's any difference.

Furthermore, please try testing on one of the machines in question by clearing the Outlook cached files located below, then launch Outlook again to check how it goes:
C:\Users\ username \AppData\Local\Microsoft\Outlook
C:\Users\ username \Roaming\Local\Microsoft\Outlook

Besides, to help eliminate whether the issue is due to any third party application installed, it's suggested to perform a Windows Clean boot on a problematic machine so as to help narrow down the issue. See How to perform a clean boot in Windows.

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Answer 3

I solved this issue by disabling COM add-ins one by one in (outlook) Safe Mode until the culprit was found.

Answer 4

I could not start in standard or safe mode. Only administrator mode. I solved it by running a "Microsoft Defender Offline Scan"