MICROSOFT has issued a rare “critical” update to Outlook users after millions of users were left unable to access their emails.
The emergency fix follows weeks of disruption for Microsoft customers after a major Windows 11 security update released earlier this month.
People using cloud-only Microsoft 365 email accounts were not affected by the bugCredit: Alamy
In response, rolled out a new emergency “out-of-band” update called KB5078127, which users need to install to fix the Outlook crashes and email access problems.
The update was released last week and is only issued when serious bugs cannot be left unresolved.
These rare fixes are usually reserved for critical system issues, including crashes and PC reset failures.
Microsoft said the patch will be offered automatically to all users, even if they have not yet experienced any problems.
On the Update page, it appears as ‘2026-01 Update (KB5078127) (26200.7628) is available’.
The download takes just a few minutes, with installation lasting around three minutes and requiring just one reboot.
Users can also manually download KB5078127 from the Windows Update Catalogue.
Microsoft added that the update is cumulative, meaning earlier emergency patches do not need to be installed separately.
If issues continue after installing the update, users are advised to run the built-in Windows troubleshooter or contact Microsoft support.
According to Windows Latest, people using cloud-only Microsoft 365 email accounts were not affected by the bug.
However, users with a POP email account, which downloads emails directly to a computer rather than storing them in the cloud, saw their Outlook accounts glitch and crash.
Alongside Outlook failures, users have complained about slow system performance, apps refusing to open and Windows features freezing without warning.
How can I get the new update?
The update, released last week, is called KB5078127 and has been issued as an “out-of-band” fix.
These types of updates are rarely rolled out and are usually reserved for serious problems that cannot wait, such as critical system errors and PC reset failures.
Microsoft will push the patch to all users, even if they have not experienced any issues so far.
On the Windows Update page, it appears as ‘2026-01 Update (KB5078127) (26200.7628) is available’.
The download takes just a few minutes, with installation lasting around three minutes and requiring only a single reboot.
Users can also download KB5078127 directly from the Windows Update Catalogue.
Microsoft said the update is cumulative, meaning anyone who installs it will not need to apply earlier emergency fixes separately.
If issues continue, users are advised to run the built-in Windows troubleshooter or contact Microsoft support.
Eze Chidiebere Paul
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