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Find information on known issues and the servicing status for Windows 10, version 1607 and Windows Server 2016. For immediate help with Windows update issues, click here if you are using a Windows device to open the Get Help app or go to support.microsoft.com. Follow @WindowsUpdate on X (formerly Twitter) for Windows release health updates. If you are an IT administrator and want to programmatically get information from this page, use the Windows Updates API in Microsoft Graph.
Current status as of October 13, 2026
As of October 13, 2026, Windows 10 Enterprise LTSB 2016 has reached end of updates. Devices running this version will no longer receive security updates containing protections from the latest security threats. For devices running Windows 10 Enterprise LTSB 2016, we recommend updating to the latest Long-Term Servicing Channel (LTSC) release, Windows 11 Enterprise LTSC 2024.
On January 12, 2027, Windows Server 2016 will reach end of updates. Windows Server 2025 is now the latest Long-Term Servicing Channel (LTSC) release for Windows Server. To download a free 180-day evaluation, visit the Microsoft Evaluation Center.
For more information about product lifecycle dates and servicing timelines, see the Windows 10 Enterprise LTSB 2016 and Windows Server 2016 lifecycle pages, Windows Server release information page, Microsoft lifecycle website and Lifecycle FAQ - Windows.
Known issues
See open issues, content updated in the last 30 days, and information on safeguard holds. To find a specific issue, use the search function on your browser (CTRL + F for Microsoft Edge).
| Summary | Originating update | Status | Last updated |
|---|---|---|---|
| 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. | OS Build 14393.9612 KB5126868 2026-10-13 | Mitigated | 2026-10-16 21:48 PT |
| Incorrect notifications that "Microsoft Defender Antivirus is turned off" Microsoft Defender Antivirus remains active and functioning correctly despite notifications following the latest update. | N/A | Resolved | 2026-09-30 16:42 PT |
| USB audio devices might fail to start or produce no sound Some USB Audio Class 1.0 devices display Code 10 or fail in multichannel audio modes after installing the Sept. 8 update | OS Build 14393.9512 KB5123099 2026-09-08 | Mitigated | 2026-09-29 10:12 PT |
Issue details
October 2026
Users might be unable to sign in to OWA or send emails on Exchange Server
| Status | Originating update | History |
|---|---|---|
| Mitigated | OS Build 14393.9612 KB5126868 2026-10-13 | Last updated: 2026-10-16, 21:48 PT Opened: 2026-10-16, 16:19 PT |
After installing the October 2026 Windows security update (KB5126868), some on-premises Exchange servers might experience issues accessing or sending email. Users might be unable to sign in to Outlook on the web (OWA), or email messages sent from Outlook might remain in the Outbox and not be delivered. Additionally, Exchange might experience issues accessing mailboxes during mailbox replication.
In some affected configurations, Exchange Server OWA might fail with an error MapiExceptionMdbOffline: Unable to make connection to the server. (hr=0x80004005, ec=1142) with Event ID 1006 logged in the application log. Another reported symptom is growing email queues. Installing the October 2026 Exchange server security updates isn’t required for these issues to occur.
Workaround: This issue can be temporarily mitigated by modifying the registry key as described in Exchange servers may become unstable after installation of October 2026 Windows updates.
The October 2026 update introduced a default limit on the amount of memory used by Endpoint Mapper when handling Endpoint Lookup calls. For workloads such as Exchange Server, the default limit of 512 simultaneous Endpoint Lookup calls might not be sufficient under heavy load. Administrators can use this registry setting to increase the maximum number of simultaneous Endpoint Lookup calls, which increases the amount of memory that Endpoint Mapper can use.
Microsoft Support: An additional mitigation is available for affected devices through Microsoft Support. To apply this mitigation in your organization, please contact Microsoft Support for business.
Next steps: We are investigating this issue and will provide more information when it is available.
Affected platforms:
- Client: None
- Server: Windows Server 2025; Windows Server 2022; Windows Server 2019; Windows Server 2016
September 2026
USB audio devices might fail to start or produce no sound
| Status | Originating update | History |
|---|---|---|
| Mitigated | OS Build 14393.9512 KB5123099 2026-09-08 | Last updated: 2026-09-29, 10:12 PT Opened: 2026-09-25, 18:40 PT |
After installing the September 8, 2026, Windows security update (KB5123099), some USB Audio Class 1.0 devices might fail to start or produce audio. Affected devices might experience one or more of the following symptoms:
- The device displays an error in Device Manager: "This device cannot start (Code 10).”
- No audio output.
- Volume controls are unresponsive or remain at zero.
- Sound settings are unresponsive or unavailable.
- Some devices might function in standard stereo configurations but fail when using multichannel audio features, including 8-channel or 3D audio modes. Some customers have reported that they're able to restore audio in these cases by switching to 2-channel mode. (*Note: This behavior is resolved in the out-of-band update released on September 14, 2026. See Resolution section below.)
This issue is limited to USB Audio Class 1.0 devices.
Microsoft Support: IT administrators who need an immediate workaround for the symptoms not addressed yet by the OOB update should contact Microsoft Support for Business for assistance.
Resolution: This issue is partially resolved in the out-of-band (OOB) update released on September 14, 2026, (KB5129239), and updates released after this date. This OOB update resolves the symptoms experienced on devices using 8-channel or 3D audio modes (last bullet point in the list of symptoms documented in this entry). We are working to address the other symptoms and will update this documentation when more information is available.
Affected platforms:
- Client: Windows 11, version 26H2; Windows 11, version 26H1; Windows 11, version 25H2; Windows 11, version 24H2; Windows 11, version 23H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10 Enterprise LTSC 2019; Windows 10 Enterprise LTSC 2016
- Server: Windows Server 2025; Windows Server 2022; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012
August 2026
Incorrect notifications that "Microsoft Defender Antivirus is turned off"
| Status | Originating update | History |
|---|---|---|
| Resolved | N/A | Resolved: 2026-09-30, 16:42 PT Opened: 2026-08-28, 15:34 PT |
After installing Microsoft Defender Antivirus update (version 4.18.26070.9), released on August 5, 2026, notifications might appear stating that "Microsoft Defender Antivirus is turned off," even though the antivirus is functioning correctly and all settings show it as active. These notifications can appear when Windows starts and intermittently afterward. They persist even if notification settings are turned off.
This issue can be observed in any version of Windows or Windows Server with Microsoft Defender Antivirus running with the latest Defender updates.
Resolution: This issue was resolved in Microsoft Defender Antivirus update (version 4.18.26080.4), released on September 17, 2026.
Affected platforms:
- Client: Windows 11, version 26H1; Windows 11, version 25H2; Windows 11, version 24H2; Windows 11, version 23H2; Windows 10, version 22H2; Windows 10, version 21H2; Windows 10 Enterprise LTSC 2019; Windows 10 Enterprise LTSC 2016
- Server: Windows Server 2025; Windows Server 2022; Windows Server 2019; Windows Server 2016; Windows Server 2012 R2; Windows Server 2012
Report a problem with Windows updates
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Need help with Windows updates?
Search, browse, or ask a question on the Microsoft Support Community. If you are an IT pro supporting an organization, visit Windows release health on the Microsoft 365 admin center for additional details.
For direct help with your home PC, use the Get Help app in Windows or contact Microsoft Support. Organizations can request immediate support through Support for business.
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