Outage in Microsoft 365
Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled
Resolved Minor
March 12, 2026 - Started 29 days ago
- Lasted 14 days
Incident Report
Summary AI Generated
A code issue in Microsoft Teams Meeting Add-in version 26043.2016.4478.2773 caused compatibility problems with classic Outlook, resulting in application crashes and launch failures for some users. The incident affected users running classic Outlook with the problematic Teams add-in enabled. Microsoft resolved the issue by recommending users upgrade to the latest Outlook version or perform an Online Repair of Office, while also working on deploying a permanent compatibility fix.
Title: Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled
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.
As a workaround, users can also perform an Online Repair of Office or update Outlook to the latest version to resolve the issue.
Current status: We're analyzing support provided information to determine our next troubleshooting steps.
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.
Next update by: Tuesday, March 17, 2026, at 9:00 AM UTC
Components affected
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Latest Updates ( sorted recent to last )
18 days ago - at 03/23/2026 10:02AM
Title: Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled
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.
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. 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.
Current status: 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.
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.
Start time: Thursday, March 12, 2026, at 12:36 PM UTC
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.
Next update by: Monday, March 30, 2026, at 10:30 AM UTC
22 days ago - at 03/19/2026 10:25AM
Title: Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled
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.
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. 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.
Current status: We're continuing to work on deploying a fix to resolve the compatibility issue, and anticipate that this should be complete by our next scheduled update.
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.
Start time: Thursday, March 12, 2026, at 12:36 PM UTC
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.
Next update by: Monday, March 23, 2026, at 10:30 AM UTC
24 days ago - at 03/17/2026 08:54AM
Title: Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled
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.
Current status: 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.
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.
Start time: Thursday, March 12, 2026, at 12:36 PM UTC
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.
Next update by: Thursday, March 19, 2026, at 10:30 AM UTC
24 days ago - at 03/17/2026 06:55AM
Title: Some users may be unable to use classic Outlook when the Teams Meeting Add-in is enabled
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.
As a workaround, users can also perform an Online Repair of Office or update Outlook to the latest version to resolve the issue.
Current status: We're analyzing support provided information to determine our next troubleshooting steps.
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.
Next update by: Tuesday, March 17, 2026, at 9:00 AM UTC
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