This weekend's Microsoft 365 outage, which left unlucky subscribers unable to login and use its Outlook email service as expected, has been blamed on a "problematic code change" by the Windows giant.

The problems for Redmond, and its paying customers, [1]started at around 2100 UTC on Saturday. At least 30,000 Outlook users reported problems via DownDetector alone, and there are still intermittent issues for some users as the new week swung around. Now, according to Microsoft's status page, [2]everything's fine and should be working again.

"We've identified a potential cause of impact and have reverted the suspected code to alleviate impact. We’re monitoring telemetry to confirm recovery," the cloud titan [3]added in an alert on US state media.

[4]

"Following our reversion of the problematic code change, we’ve monitored service telemetry and worked with previously impacted users to confirm that service is restored."

[5]Payday from hell as several British banks report major outages

[6]Yes, Slack isn't working properly right now – enjoy your internet snow day

[7]Microsoft Azure faceplants in Norway, taking government services with it

There were some hiccups along the way, however. iOS users reported still being unable to login even after the promised fix was rolled out. In some cases they report having to delete the app from their handsets and reinstall it to get successful connectivity.

Then to add insult to injury on Monday, Redmond was again [8]warning of some downtime affecting Microsoft 365 services. For instance, some of those looking to enjoy start-of-the-week Teams meeting to catch up with coworkers were stymied and unable to use the system as hoped. Your mileage may vary: Some people have working access to M365, some don't.

[9]

We've asked Microsoft for clarification about the issues that have caused the bumpy service and will update as more information comes in.

That said it hasn't been the greatest of starts to the year for Microsoft on the outages front. Last month Azure [10]took a dive for Nordic customers, and in January 365 login [11]problems led to a lot of customers having a bad case of the Mondays - made worse coming after another Azure [12]outage a few days beforehand. ®

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[1] https://x.com/MSFT365Status/status/1895950750750060583

[2] https://admin.microsoft.com/servicestatus

[3] https://x.com/MSFT365Status/status/1895988083574681941

[4] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offprem/saas&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=2&c=2Z8Y0kHKFsntpXb-3spyrPwAAAMs&t=ct%3Dns%26unitnum%3D2%26raptor%3Dcondor%26pos%3Dtop%26test%3D0

[5] https://www.theregister.com/2025/02/28/payday_from_hell_as_several/

[6] https://www.theregister.com/2025/02/26/slack_outage/

[7] https://www.theregister.com/2025/02/20/microsoft_azure_outage_norway/

[8] https://x.com/MSFT365Status/status/1896621905206976550

[9] https://pubads.g.doubleclick.net/gampad/jump?co=1&iu=/6978/reg_offprem/saas&sz=300x50%7C300x100%7C300x250%7C300x251%7C300x252%7C300x600%7C300x601&tile=4&c=44Z8Y0kHKFsntpXb-3spyrPwAAAMs&t=ct%3Dns%26unitnum%3D4%26raptor%3Dfalcon%26pos%3Dmid%26test%3D0

[10] https://www.theregister.com/2025/02/20/microsoft_azure_outage_norway/

[11] https://www.theregister.com/2025/01/13/azure_m365_outage/

[12] https://www.theregister.com/2025/01/10/microsoft_azure_networking_snafu/

[13] https://whitepapers.theregister.com/