TheRobins Posted March 19 Posted March 19 Just FYI, we are using 2021 LTSC here and no one can open outlook at all. Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled Issue ID: EX1254044 Affected services: Exchange Online Status: Service degradation Issue type: Incident Start time: 12 Mar 2026, 12:36 GMT User impact Users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled. More info Specifically, impacted users may experience crashes while using the classic Outlook on any client, or be unable to launch the service. While we work on the permanent fix, we recommend impacted users upgrade to the latest Outlook version. Scope of impact Some users that are attempting to use classic Outlook with the Microsoft Teams Meeting Add-in version 26043.2016.4478.2773 enabled may be impacted. This information may be updated as our investigation continues. Root cause A code issue within a recent Microsoft Teams Meeting Add-in update under version 26043.2016.4478.2773 is causing a compatibility issue with classic Outlook and resulting in functionality issues. Current status 17 Mar 2026, 08:54 GMT We've identified a code issue within a recent Microsoft Teams Meeting Add-in update under version 26043.2016.4478.2773, which is causing a compatibility issue with classic Outlook, and resulting in functionality issues. We've confirmed that the previous Microsoft Teams version 26032.208.4399.5 works successfully with classic Outlook, though we recommend affected users that are on the latest updated Microsoft Teams version to also upgrade to the latest Outlook version to avoid further complications. We're working on deploying a fix to resolve the compatibility issue, and we anticipate being able to provide a remediation timeline by our next scheduled update. Next update by: Thursday, 19 March 2026 at 10:30 GMT
Fazza Posted March 19 Posted March 19 Until you get a fix, have you tried holding down the CTRL key and then clicking/double-clicking on the Outlook icon? Safe mode should open Outlook without any add-ins running so maybe it will open for you.
TheRobins Posted March 19 Author Posted March 19 Sadly not, they have done a good job on breaking it. Even removing teams and the add-in will not work as the damage is already done.
BigAndyD Posted March 23 Posted March 23 Has this been resolved yet? We are getting a number of users complaining.
TheRobins Posted March 23 Author Posted March 23 All good this morning for us, wasnt working last thing on Friday when I checked. I didnt do anything or have any updates to apply, possibly it was infrastructrure side they rolled the update out. to?>
TheRobins Posted March 23 Author Posted March 23 Further, a new update on 365 Admin page. "We've determined that the aforementioned fix isn't a viable option due to impact occurring due to outdated versions causing the incompatibility and recommend if you're affected by this event that you update to the latest Classic OutlookWin32 version. However, please reach out to your support representatives to request a temporary reversion if you require additional time to upgrade your Outlook version." Worth triggering a click to run update on the affected machines?
Gongalong Posted March 23 Posted March 23 We have very few staff using the Outlook app, but had a case this morning. We uninstalled and relnstalled the latest, and that resolved it. Not great though if you have lots of staff using the app. Some further workarounds in the support article https://support.microsoft.com/en-gb/office/classic-outlook-crashes-and-opens-in-safe-mode-starting-march-12-2026-0f1b0427-e259-438d-aa93-78128ae61f80
MrEprise Posted March 23 Posted March 23 This fix seems to work and doesn't require re-installing or updating Office. Quote The Teams add-in version installed here: 1.26.02603 is known to get corrupted when Microsoft Teams updates. Fix by reinstalling it: Close Outlook and Teams Delete this folder: C:\Users\%username%\AppData\Local\Microsoft\TeamsMeetingAdd-in Start Teams again Teams will reinstall the add-in automatically. 1
MatthewL Posted March 23 Posted March 23 Had a few of these last week, just went into Word or Excel and ran updates and let it complete and it fixes it.
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