Outlooks keep crashing

Catherine Stannard 140

When i go to send an email, try to right click on a spelling mistake or add a snapshot - The email crashes and closes down not even saving into drafts? please can anyone advise?

Moderator note: thread updated with version of Outlook (classic Outlook for Windows)

Laurenz-7348 20 Reputation points

2026-06-30T08:13:32.0933333+00:00

Same issue here, affecting our users for the past few hours: right-clicking inside a new email crashes Outlook, with mso.dll appearing to be the cause. Safe Mode does not resolve it for us either.
Jason Groenewald 5 Reputation points

2026-06-30T08:20:05.8133333+00:00

We are experiencing the exact same problem with our clients.
Freuding, Jan 30 Reputation points

2026-06-30T08:24:18.14+00:00

Yes, we're having the same problem with several users and customers. Outlook crashes when you right-click in a new email.
Eric L 25 Reputation points

2026-06-30T08:30:58.0866667+00:00

Same thing here, crash on right click. Safe mode or recreating the outlook profile does not help
Bojan Džaja 10 Reputation points

2026-06-30T08:44:38.2233333+00:00

Also, in our environment we have the same problem on hundreds of computers.
Patrick Müsken 5 Reputation points

2026-06-30T08:52:40.0366667+00:00

we see the same behaviour on machines with the latest Outlook Build 20026.20182 on Windows 11
the machines with Build 20026.20166 are working fine.

Safe-Mode did not help
New Oulook-Profile does not help
Disabing the spell checking (the wriggly red lines on typos) did not help
Cameron 15 Reputation points

2026-06-30T08:54:57.21+00:00

Same issue here, started today 30/06/2026. Outlook (not "new Outlook") Win 11 V 2605 build 20026.20182

To clarify, outlook is crashing on command as soon as I right click the message body. There doesn't need to be a spelling error, there doesn't even need to be any text. I can boot, open outlook, start a new email, right click on the message body, and it crashes to desktop. It also crashes when pressing the context menu key on the keyboard. So obviously it's Outlook's context menu that is crashing Outlook.

Right clicking on the subject line, the address fields, navigation pane, folders etc are fine, it's just the message body that crashes it.
Keith Wilson 10 Reputation points

2026-06-30T08:56:18.9366667+00:00

I have the same problem. Started yesterday. I am using Outlook classic.
Paul 15 Reputation points

2026-06-30T09:05:08.07+00:00

Same issue for us Build 20026.20168. New profile, same issue. Safe mode, same issue. Only some users affected. WIth problem users, every time they right click, outlook crashes. Event viewer shows:

Faulting application name: OUTLOOK.EXE, version: 16.0.20026.20168, time stamp: 0x6a23f14f

Faulting module name: mso.dll, version: 0.0.0.0, time stamp: 0x6a23ee6b

Exception code: 0xc0000005

Fault offset: 0x00000000000f349c

Faulting process id: 0x7c84

Faulting application start time: 0x01dd08603807bdaa

Faulting application path: C:\Program Files\Microsoft Office\root\Office16\OUTLOOK.EXE

Faulting module path: C:\Program Files\Common Files\Microsoft Shared\Office16\mso.dll

Report Id: bdb2e8cd-4cb8-4e9c-8ab9-09d65ca06a98

Faulting package full name:

Faulting package-relative application ID:
Cameron 15 Reputation points

2026-06-30T09:06:26.6566667+00:00

TENTATIVE UPDATE:

Rebooted twice, issue persists.

Rebooted a third time, issue appears to be resolved. No additional debugging, just a simple reboot (thrice).

I will monitor and update if issue returns.

Additional edit - it appears that the third reboot prompted outlook to update to 20131.20090, which other users are reporting is a bug fix for exactly this.
Anonymous

2026-06-30T09:12:01.2933333+00:00

Have you tried restarting the machine @Paul ? Some users have reported that it may take 2 - 3 reboots to fully resolve the issue. You might also want to consider updating to the latest version (20090). https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date#version-history
RossCrooks-7034 0 Reputation points

2026-06-30T09:23:11.36+00:00

Updating outlook to 2606, Build: 20131.20090 fixes this issue for us.
Paul 15 Reputation points

2026-06-30T09:51:48.92+00:00

I haven't rebooted, we are using Citrix and these effectively reimage when rebooted. Just trying Outlook 2606 Build: 20131.20090...Fingers crossed
Andy Crook 10 Reputation points

2026-06-30T09:55:09.24+00:00

Run Online Repair, it updates to 2606 (20131.20090).

Fixes it in 10 minutes
Andy Crook 10 Reputation points

2026-06-30T10:11:54.2866667+00:00

Run an Online Repair, will update to 2606(20131.20090)

Takes 10-15 minutes and works first time
Cookie Monster 0 Reputation points

2026-06-30T10:22:01.5433333+00:00

Use Online Update in any of the Office Applications to update to
Version 2606 (Build 20131.20090)
Paul 15 Reputation points

2026-06-30T10:29:43.01+00:00

Tested on 3 users with the version 2606 Build: 20131.20090. Issue now resolved for them! thanks @RossCrooks-7034 and @Anonymous !
faca5 6 Reputation points

2026-06-30T10:34:21.6766667+00:00

Hello.

We are experiencing the same issue on our side.

While writing messages, the window has already closed several times today, and Outlook has also crashed occasionally. We have now updated with the latest patches.

We hope the issue has been resolved.
Keith Wilson 10 Reputation points

2026-06-30T11:17:28.69+00:00

Running 365 online repair also works
Alex Tovey 5 Reputation points

2026-06-30T13:53:14.01+00:00

All my clients are up to date, outlook still having those issues currently its up to 124 Windows 11 computers, 6 MACs and 12 Windows 10 machines.

This is all linked with office 365.
Anonymous

2026-06-30T14:16:37.9233333+00:00
Have you created ticket in Admin center to report this to Microsoft @Alex Tovey

Aside from updating, you could also try rolling back Outlook to version 20168- Open an elevated Command Prompt (search for Command Prompt, right‑click, and choose Run as administrator).

Run the following command: "%programfiles%\Common Files\Microsoft Shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.20026.20168

For macOS, could you also share the Outlook version where the issue occurs, along with the macOS version?

From what I can see, the latest Outlook for Mac version is June 23, 2026 - 16.110.1 (26062112), so it would be helpful to confirm whether you’re on this version or an earlier one.
Anonymous

2026-06-30T14:43:38.4166667+00:00

@Alex Tovey @Anonymous I submitted a bug for this issue this morning. The Outlook Escalation Engineers debugged it and found that it was already tracked as fixed by a Word bug. The fix is in Current Channel 20103.00000 and fixed in Monthly Enterprise Channel in builds 20131.00000 and 20228.00000. I will have to check further if this somehow got into Mac Outlook. If you update clients to the latest build per respective channel, are you still seeing the issue? You can see the latest updates on Update History, https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date?.
Anonymous

2026-06-30T15:00:37.47+00:00

Hello @Anonymous thank you so much for the quick update and for your support on this, really appreciate you jumping on it so fast. And sorry for the ping earlier as well.

Hopefully the fix rolls out broadly soon and helps resolve the issue for everyone still affected. I’ll also continue to monitor from my side and check whether users are still seeing the same behavior after updating to the latest builds.
Anonymous

2026-06-30T15:06:53.91+00:00

thanks for the heads up on this. Just to make sure, the fixed builds are already out for this issue. Any customer currently hitting this issue can address it by updating to the latest build on the respective channels. If you find that is not true anywhere, please let me know.

To update your Outlook build, click File, Office Account, Update Options, Update Now.
Kelly Linn 0 Reputation points

2026-06-30T20:41:11.73+00:00

Yes, mine is doing the same thing!
Vignesh Vivekanandhan 20 Reputation points

2026-07-01T06:24:23.69+00:00

Hi Team,

We are continuing to experience issues with the New Outlook. Several users within our company have reported the same problem, and some of our customers are experiencing it as well.

We have also tested on a freshly provisioned laptop, but the issue persists.

When users click on emails or any other options within Outlook, the application becomes unresponsive and no action is performed.

Could you please investigate this issue and advise on the next steps?

Thank you.
Anonymous

2026-07-01T09:02:42.48+00:00

Hi @Vignesh Vivekanandhan since the issue is affecting several users in your company and even some customers, at this point I think it would be best to collect the Outlook version and Windows version from all affected machines, then open a support ticket with Microsoft Support as soon as possible so they can investigate this from the backend side.Before doing that, I would still suggest making sure the affected devices have already been updated to the latest available version. Microsoft released Version 2606 (Build 20131.20112) on June 30, which includes fixes for this issue. If the affected users are not on this build yet, please update Outlook/Microsoft 365 Apps first and test again.

https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date?#version-history

If the issue still happens after updating, please also check whether the affected users are using the 32-bit version of Office/Outlook. Some users have reported that the issue affected the 32-bit version, and moving to the 64-bit version, then updating to the latest build, resolved the problem for them.

In addition, one user in this thread, Eric, mentioned that deleting the following registry key helped in their case: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\ExperimentConfigs

You may want to test this on one affected machine first before applying it more broadly.
JK 0 Reputation points

2026-07-01T10:50:53.4333333+00:00

Read online this issue is affecting thousands of people who have had an update, how long is this going to take Microsoft to resolve as this is causing massive issues for everyone, not just us.

Microsoft please update us all when this issue will be resolved.
Vignesh Vivekanandhan 20 Reputation points

2026-07-01T11:05:54.44+00:00

Hi @Anonymous

thanks, we have tried the same still no luck. when user tried open the email, or click settings nothing happens.

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\ExperimentConfigs this is not available for the machine
Anonymous

2026-07-01T11:50:55.8633333+00:00

Hello @JK

First, I'm sorry for the inconvenience this issue has caused. I completely understand the impact, especially when it affects daily work across multiple users.

From what I've seen, Microsoft became aware of the issue and began investigating it shortly after reports started coming in. It also appears that a fix has already begun rolling out, with some users reporting improvement after updating to the latest available build.

If you're still experiencing the problem, please make sure you're running the most recent version available to your update channel and let me know whether the crashes continue after updating.

Microsoft is still actively investigating the issue and working toward a broader official resolution for any users who remain affected. Unfortunately, as this is a public user-to-user forum, I don't have access to internal timelines or the ability to provide ETA information.

Again, I apologize for the disruption this has caused. If Microsoft releases any significant updates, I'll post them in this thread as soon as they become available.

Thank you for your patience and understanding.
Anonymous

2026-07-01T11:53:33.84+00:00

Well @Vignesh Vivekanandhan to be honest, at this point, I'm not sure what else I can realistically suggest from the forum side.How is your support ticket progressing? Microsoft is still actively investigating this issue, so there is currently no confirmed resolution or additional workaround that I can recommend.
JK 0 Reputation points

2026-07-01T11:58:30.7166667+00:00

Stupid thing is we did not do any Office or Outlook update, all we did was a Windows Update ands that must have included updating Outlook and has caused the crash, when I go to Outlook it says no updates available.
Anonymous

2026-07-01T12:21:25.85+00:00

From what I've seen, this does not appear to be caused solely by an Outlook update. You may want to refer to Gabe's response (Microsoft employee) for additional details and context regarding the ongoing investigation.

Also, when you say Outlook reports "no updates available," could you share your exact Outlook version and build number @JK ?
JK 0 Reputation points

2026-07-01T12:34:47.4766667+00:00

Outlook 365 build number 20131.20090
Anonymous

2026-07-01T13:04:11.42+00:00

If you're already on build 20090, you might want to try a few more restarts and see if the issue resolves itself @JK . I've seen reports from some users that after running an Office Repair, the newer update became available, or that the issue was resolved after a couple of reboots once the latest build had been installed.

If that doesn't help, I'd recommend opening a support ticket with Microsoft so they can investigate your specific case further. Unfortunately, there isn't much more we can do from the forum side while Microsoft is still actively investigating the issue.
JK 0 Reputation points

2026-07-01T13:21:33.77+00:00

We have done this many times and it still does not work, a friend has outlook 2016 and called me and asked if we had the same issue so it appears this is not a office 365 issue as they are on a 10 year old outlook 2016 build and have the same issue.
Varian, Brian 0 Reputation points

2026-07-01T14:18:27.4533333+00:00

This seems to now be acknowledged by Microsoft. https://admin.cloud.microsoft/?#/servicehealth/:/alerts/EX1409958
Todd Nichols 0 Reputation points

2026-07-01T16:40:01.7433333+00:00

I am having the same issues right clicking. I can’t cut and paste from other documents into an email. It’s quite a pain in the ass and I have seen a fix come out yet.
Stefan Blom 352.5K Reputation points MVP Volunteer Moderator

2026-07-01T18:16:02.6166667+00:00

We are continuing to experience issues with the New Outlook.

@Vignesh Vivekanandhan

Most people reporting this seem to be running the classic Outlook. If you are seeing a problem in the new Outlook, maybe you should start a new thread, to get more attention for your question.

See also the support overview at https://support.microsoft.com/en-US/Support/known-issues/fixes-or-workarounds-for-recent-issues-in-new-outlook-for-windows .
Norman Hillbish 0 Reputation points

2026-07-02T13:13:27.4266667+00:00

Same problem here. And after applying Windows updates to a user machine with this symptom, Outlook will not load.

Thanks, Microsoft. Is there a chart available that shows the negative effects of Microsoft security updates?

Seems like each update introduces a bug that is fixed in a later update. Microsoft updates = more Helpdesk tickets.
Anonymous

2026-07-02T14:33:07.7433333+00:00

Hello @Todd Nichols how is this issue progressing on your side?

I recently received information that Microsoft has released a fix today which appears to improve this issue. Could you please recheck?
Anonymous

2026-07-02T14:50:24.7233333+00:00

Hi @Vignesh Vivekanandhan

I wanted to follow up and see how this issue is going. I recently received information that Microsoft released a fix today which should improve this issue.

Could you please recheck and let us know if the problem persists?

Sorry for the delayed response, and thank you for your patience. I look forward to your feedback.

Answer accepted by question author

James Burney 150

We have some users that were affected by this issue. The version was 20026.20182. Typical fixes such as Quick Repair did not resolve the issue.

Updating to the latest version of Office apps resolved the issue for the users. The latest version is 20131.20090 and was released on June 25.

To update the apps on one machine, go to: Outlook > File > Office Account > Update Options > Update Now

Catherine Stannard 140 Reputation points

2026-06-30T10:48:28.9566667+00:00

Hi James - This appears to have worked! thank you :-)
Joël Brunner 0 Reputation points

2026-06-30T14:07:46.9933333+00:00

Can confirm that updating to the most recent version 2606 resolved the issue for our customers.
Margot Fitzgerald 0 Reputation points

2026-06-30T18:58:42.7133333+00:00

This worked for me too!!! Thank you.
Diksha Deovansh 0 Reputation points

2026-06-30T20:27:48.05+00:00

Online repair can fix this as I did it with multiple users.
Kevin L 5 Reputation points

2026-06-30T21:38:56.1133333+00:00

Repair did not fix this issue and I know of someone who experienced it on version 16.0.20026.20168. This is not just tied to 16.0.20026.20182. However, yes, updating to 16.0.20131.20090 does resolve the issue.
M F M ZAKEER 0 Reputation points

2026-07-01T08:08:22.8266667+00:00

Based on my observations, the issue occurs only for users running Microsoft 365 Apps Version 20026.20182 (32-bit). Users running the 64-bit edition do not experience the issue. Therefore, I plan to uninstall the 32-bit version and reinstall the 64-bit edition for all affected users.
Daniel Segura Salazar 0 Reputation points

2026-07-01T16:05:05.7266667+00:00

Hi

Does any one know how to download the office offline installer, normaly I was able to create the XML file from the web site https://config.office.com/deploymentsettings, then with CMD download the package with all the binaries and files necesaries using the command setup.exe /download configuration.xml, it downloads and the with the command setup.exe /configure configuration.xml it installed. But now it fails to be installed, there is something wrong with the installer.

This is necessary to make the update process to 2606 with the fix of this Outlook error, because online repair takes a lot to be completed

If anyone knows how to get this offline installer and use it, I will be more than glad.

Regards
Will Lambirth 0 Reputation points

2026-07-01T18:31:26.7666667+00:00

I have multiple users having issues. They are all on 20131-20112. I’ve tried multiple restarts. Windows updates. Office Updates. Quick Repair. Full uninstall and reinstall. Full profile rebuild. Nothing has helped to resolve the issue.
JK 0 Reputation points

2026-07-01T18:44:57.67+00:00

M F M ZAKEER •

Follow

0Reputation points

Jul 1, 2026, 9:08 AM

Based on my observations, the issue occurs only for users running Microsoft 365 Apps Version 20026.20182 (32-bit). Users running the 64-bit edition do not experience the issue. Therefore, I plan to uninstall the 32-bit version and reinstall the 64-bit edition for all affected users.

I am running the 64 bit edition and having issues, as mentioned I have friends back on outlook 2016 with the same issue, it makes me wonder if this issue is deeper then just Outlook as some of my 2016 friends only report having this issue after a Windows 10 update and they have not updated the Outlook at all.
JK 0 Reputation points

2026-07-01T18:48:11.52+00:00

Think this issue is deeper then Microsoft is telling us all.
Norman Hillbish 0 Reputation points

2026-07-02T13:15:48.56+00:00

Has Office Repair ever fixed an issue for anyone here? Can one person say they had a problem, and Office Repair tool was the solution? We have never seen it work. The team is getting pretty sick of wiping machines.

14 additional answers

Eric L 25 Reputation points

2026-06-30T09:03:36.4266667+00:00
Renaming / Deleting the Registry Key
```
HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\ExperimentConfigs
```
fixed it for me
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Sherwin Kooij 0 Reputation points

2026-06-30T12:19:35.8933333+00:00

We used this and it was a instant fix

Festin, John Clifford 0 Reputation points

2026-06-30T22:24:36.2333333+00:00

Which you have deleted?
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Andreas H 20 Reputation points

2026-06-30T08:24:58.94+00:00

Hello Abhay,

I am an Admin in my company and see the same issue on a variety of pcs from different manufacturers. I would therefore rule out drivers as the cause.

Version: Outlook Classic Version 2605 Build 20026.20182

Starting in safe mode did not resolve the issue. Doing an Office repair (both quick and online) did not resolve the issue.

To be sure, I tried to replicate the issue on a newly installed computer with no 3rd party software besides Office. Outlook crashes on this machine too, as soon as you right click on an e-mail.

Windows log shows C:\Program Files\Common Files\Microsoft Shared\Office16\mso.dll as faulty module.

Edit: I checked on three clients if there were updates installed prior to the problem showing up. All three installed the latest office patch this morning. A colleague of mine does not have the issue, no update was installed on his pc.
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Laurenz-7348 20 Reputation points

2026-06-30T08:27:24.5133333+00:00

Can confirm — this doesn't seem to be endpoint-related. We're getting a lot of reports from our terminal server users as well.

Laurenz-7348 20 Reputation points

2026-06-30T08:32:44.7766667+00:00

Our affected users are still on Build 20026.20182

Andy Crook 10 Reputation points

2026-06-30T09:54:23.3066667+00:00

Run an Online Repair, fixes it straight away ( updates to 2606 (20131.20090).

Takes 10 minutes
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Anonymous

2026-06-30T08:43:08.48+00:00
Dear @Catherine Stannard @Andreas H @Eric L @Freuding, Jan @Jason Groenewald @Laurenz-7348 @Jason Groenewald and everyone thank you for reporting this issue.

Microsoft has recently received several reports about this issue and is currently actively investigating it. Based on current reports, actions such as updating, repairing Office, or creating a new profile have not resolved the problem, and it may persist across devices and network connections.

Since the issue you’re seeing seems to occur on 20182, it may be worth either:
- rolling back to version 20168
  
  Open an elevated Command Prompt (search for Command Prompt, right‑click, and choose Run as administrator).
  
  Run the following command: "%programfiles%\Common Files\Microsoft Shared\ClickToRun\officec2rclient.exe" /update user updatetoversion=16.0.20026.20168
- or updating to version 20090 https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date#version-history
Sorry for any inconvenience this may be causing.
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Andreas H 20 Reputation points

2026-06-30T08:51:19.4033333+00:00

This worked for me.

Jason Groenewald 5 Reputation points

2026-06-30T08:52:26.8333333+00:00

Once we rolled back, do we need to pause updates until further notice?

Laurenz-7348 20 Reputation points

2026-06-30T08:52:59.9633333+00:00

So we should downgrade two versions? That seems odd given the issue only started this morning. This points to something that changed on the backend rather than the client.

Our users report this issue even on 20026.20182 (not the latest patch)

Anonymous

2026-06-30T09:03:54.1566667+00:00

Well, the version I suggested is earlier than 20182, since 20182 itself had some known issues with Copilot.

As of today, a fix is being rolled out in version 20090. Since the issue you’re seeing seems to occur on 20182, it may be worth either:

rolling back to version 20168, or

updating to version 20090

and then checking if that stabilizes things on your sides @Andreas H @Bojan Džaja @Laurenz-7348 @Jason Groenewald

https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date#version-history

Laurenz-7348 20 Reputation points

2026-06-30T09:05:44.31+00:00

Thanks, Gabriel. We'll give the upgrade a try.

Sarah Cushing 0 Reputation points

2026-06-30T09:49:57.31+00:00

hi - i've done this but the problem is still happening. email closes every time i right click in a table

Anonymous

2026-06-30T09:55:56.7233333+00:00

Have you tried restarting the machine @Sarah Cushing ? Some users have reported that it may take 2 - 3 reboots to fully resolve the issue.

Also, when you mentioned you’ve already done this, could you clarify exactly what steps you’ve taken? May I confirm, have you already updated to version 20090 and are still experiencing the same issue?

Sarah Cushing 0 Reputation points

2026-06-30T10:11:40.3033333+00:00

@Anonymous it's all sorted now thank you... i rolled back as per your suggestion above, and the problem was still there. i then did a repair as per @Andy Crook message and i guess it updated to 20090 as it's now all ok :)

thanks both

Kevin L 5 Reputation points

2026-06-30T21:36:57.15+00:00

I know of someone who experienced this same crashing issue with version 16.0.20026.20168 today. They had not updated to 16.0.20026.20182.

Updating to 16.020131.20090 as everyone else has stated did resolve the issue.

Ben White 0 Reputation points

2026-07-01T11:42:49.0366667+00:00

FYI, I've got reports from 2 users here which have had version 2606 build 20131.20090 installed. My sample size is only 8 total users here, one person was resolved with a reboot which might indicate the update hadn't fully completed yet.

Anonymous

2026-07-01T11:59:53.33+00:00

Hello @Ben White as I mentioned earlier, the downgrade/upgrade is only a temporary workaround at this time.

May I ask whether you've already tried updating to Version 2606 (Build 20131.20112), which was released on June 30? https://learn.microsoft.com/en-us/officeupdates/update-history-microsoft365-apps-by-date?#version-history

Microsoft is still actively investigating this issue and working toward a broader official resolution for any users who remain affected. As this is a public user-to-user forum, I don't have access to internal timelines or the ability to provide an ETA for a permanent fix.

Thank you for your patience and understanding. If I receive any significant updates from Microsoft, I'll be sure to post them in this thread.

Ben White 0 Reputation points

2026-07-01T12:06:38.0933333+00:00

@Anonymous Thanks for the tip on yesterday's release, and for keeping us all up to date 🙏🏻.
I really just made my comment to let people know of my experience. Each user was already on the latest version (at the time), according to my monitoring and it seemed a reboot was needed before the fix applied. Both these users don't seem to be having the issue on build 20131.20090 after the reboot.
If the issue does come up again for them, I'll be sure to try Build 20131.20112 first.
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Mika 0 Reputation points

2026-07-08T13:52:33.6433333+00:00
Hello everyone,

our company is experiencing almost the same issues, but the trigger appears to be different. No matter what we do, Classic Outlook keeps freezing — even when simply scrolling through emails. It happens regardless of how Outlook is being used.

We have been analyzing and testing possible causes for more than a week now.

At the moment, the most effective workaround for us is switching users to the new Outlook. However, while it does not suffer from the freezing issues, it comes with other problems of its own.

The issue mainly affects one department within the company, but it seems to be spreading to other users as well. For some users, Outlook freezes only once per day; for others, it freezes every 30 seconds.

We did not deploy any updates ourselves. The problem simply appeared overnight from Sunday to Monday last week.

After performing an Online Repair, Outlook worked normally for a few hours for some users, but then suddenly became unusable again.

Troubleshooting steps already attempted
- Restarting Outlook
- Restarting Outlook multiple times
- Office Online Repair
- Complete Office reinstallation
- Downgrading to the following versions:
  
  2606 (Build 20131.20112)
  
  2606 (Build 20131.20090)
  
  2605 (Build 20026.20182)
  
  2605 (Build 20026.20168)
  
  Even Outlook 2401 (Build 17231.20182)
  
  Deleting:
  
  HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\ExperimentConfigs
  
  Temporarily disabling and immediately re-enabling the setting: "Turn on shared calendar improvements"
- Setting RestUpdatesForCalendar to 1 in the registry:
  HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\Calendar
  
  Uninstalling Windows Updates:
  
  KB5074109
  
  KB5073724
- Deleting and recreating the PST file
At this point, we are running out of ideas. Has anyone found a root cause or a reliable workaround for this issue?
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Anonymous

2026-07-10T07:09:20.35+00:00

Hi @Mika sorry for the delayed response. Have you submitted a support request in the Microsoft 365 Admin Center for tenant-related troubleshooting?

Mika 0 Reputation points

2026-07-10T07:12:59.3266667+00:00

Hey Gabriel, Where is the best place to submit this Ticket ?

Anonymous

2026-07-10T08:06:10.2166667+00:00

@Mika Based on your description, this appears to be a different issue. As I understand it, Outlook is freezing temporarily and then recovering, rather than crashing outright.I recommend opening a support ticket through the https://admin.microsoft.com/AdminPortal/#/homepage so the support team can review the backend logs and service health for your tenant. They will be in a better position to determine whether this is an isolated tenant-specific issue or part of a broader service-related problem.
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Outlooks keep crashing

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