Investigating
We are aware of an ongoing issue affecting Microsoft 365, which may impact services that rely on Microsoft platforms.
If you have raised a support case via the Pulsant portal or email and are not receiving the support or updates you require, particularly if the issue is urgent, please contact the Pulsant Support Desk directly on:
0345 119 9999
You can continue to access the support portal here: https://portal.pulsant.com/ and email us via support@pulsant.com
Microsoft are reporting a major service outage starting at 18:00 on 12/11/2026.
Latest updates: Microsoft service health status
Update from Microsoft at 20:30:
While we haven't identified any recent changes that correlate with the start of impact, our investigation indicates the failed health checks may originate from a specific component on the affected servers that's responsible for processing them. We're deploying a targeted change to bypass this component on a subset of servers to validate whether this restores availability, and we've taken steps to prevent additional servers from being removed from service while we work to return the affected servers to service. We're also investigating why affected servers are experiencing elevated processor usage while handling requests.
While validating the targeted change, we found that many of the affected servers have become unresponsive, which is preventing us from confirming whether the change is effective. We're restarting these servers so they can come back online with the change in place, and we're applying the same approach to additional affected portions of our infrastructure to validate the results more broadly.
Potentially impacted services include:
- Exchange Online
- Microsoft Teams
- SharePoint Online
- Microsoft Copilot 365
- Microsoft Defender XDR
- Microsoft Planner
- Microsoft To Do
Update from Microsoft at 19:30:
We're aggressively pursuing all pathways to reduce impact. As a precaution, we've paused all deployments and configuration changes while we review recent changes for any correlation to this event. We've determined that the elevated load isn't driven by an overall increase in traffic, but by a large number of servers being unexpectedly unavailable, which is shifting load onto the remaining infrastructure. We're investigating what's causing these servers to become unavailable while we work to safely return them to service.
Potentially impacted services include:
- Exchange Online
- Microsoft Teams
- SharePoint Online
- Microsoft Copilot 365
- Microsoft Defender XDR
If you have raised a support case via the Pulsant portal or email and are not receiving the support or updates you require, particularly if the issue is urgent, please contact the Pulsant Support Desk directly on:
0345 119 9999
You can continue to access the support portal here: https://portal.pulsant.com/ and email us via support@pulsant.com
Microsoft are reporting a major service outage starting at 18:00 on 12/11/2026.
Latest updates: Microsoft service health status
Update from Microsoft at 20:30:
While we haven't identified any recent changes that correlate with the start of impact, our investigation indicates the failed health checks may originate from a specific component on the affected servers that's responsible for processing them. We're deploying a targeted change to bypass this component on a subset of servers to validate whether this restores availability, and we've taken steps to prevent additional servers from being removed from service while we work to return the affected servers to service. We're also investigating why affected servers are experiencing elevated processor usage while handling requests.
While validating the targeted change, we found that many of the affected servers have become unresponsive, which is preventing us from confirming whether the change is effective. We're restarting these servers so they can come back online with the change in place, and we're applying the same approach to additional affected portions of our infrastructure to validate the results more broadly.
Potentially impacted services include:
- Exchange Online
- Microsoft Teams
- SharePoint Online
- Microsoft Copilot 365
- Microsoft Defender XDR
- Microsoft Planner
- Microsoft To Do
Update from Microsoft at 19:30:
We're aggressively pursuing all pathways to reduce impact. As a precaution, we've paused all deployments and configuration changes while we review recent changes for any correlation to this event. We've determined that the elevated load isn't driven by an overall increase in traffic, but by a large number of servers being unexpectedly unavailable, which is shifting load onto the remaining infrastructure. We're investigating what's causing these servers to become unavailable while we work to safely return them to service.
Potentially impacted services include:
- Exchange Online
- Microsoft Teams
- SharePoint Online
- Microsoft Copilot 365
- Microsoft Defender XDR