UrgencyCritical · 1 exploited
RiskHigh · 1 open issue
Confirmed
Windows release health · Windows 10, version 1809 and 5 more versions
Users might be unable to sign in to OWA or send emails on Exchange Server
Issue reported on Exchange Server 2016, 2019, and Subscription Edition, affecting OWA sign-in and mail delivery.
What to do
Microsoft confirmed it and lists no fix yet. Check whether your devices match the symptoms before rolling out KB5126651 broadly.
4Days open since KB5126651
6/6Windows versions where it is open
16 OctLast updated by Microsoft · 1d ago
Status on each Windows version
Microsoft can list one issue differently per version| Windows version | Status | Caused by | Fixed by | Updated |
|---|---|---|---|---|
| Windows 10, version 18092019 () LTSC | Confirmed | KB5126651 · 13 Oct | Not yet | 16 Oct |
| Windows Server 2019 | Confirmed | KB5126651 · 13 Oct | Not yet | 16 Oct |
| Windows 10, version 1607 | Confirmed | KB5126868 · 13 Oct | Not yet | 16 Oct |
| Windows Server 2016 | Confirmed | KB5126868 · 13 Oct | Not yet | 16 Oct |
| Windows Server 2025 | Confirmed | KB5126646 · 13 Oct | Not yet | 16 Oct |
| Windows Server 2022 | Confirmed | KB5126655 · 13 Oct | Not yet | 16 Oct |
The update that caused it
What changed
First observed 17 Oct 2026No field changes in the recorded history.
Cite this recorded revision to keep the same title, summary, facts and links when the page changes.
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