Marking the end of an era, Microsoft has released Windows 10 KB5066791 cumulative update, the final cumulative update for the operating system as it reaches the end of its support lifecycle.
It should be noted that users will still be able to receive Extended Security Updates (ESU) for 1 year (consumer) and 3 years (enterprise).
The Windows 10 KB5066791 update is mandatory, as it includes Microsoft’s October 2025 Patch Tuesday security update, which addresses six zero-day vulnerabilities and 172 other flaws.
Windows users can install this update by going to settingsclicking on Windows Update, and performing manually ‘check for updates,
However, since this update is mandatory, it will automatically start installing in Windows as soon as it checks for updates. To make it more manageable, you can set a time when your computer restarts to finish the installation.
Source: BleepingComputer
After you install this update, Windows 10 22H2 will be updated to build 19045.6456, and Windows 10 21H2 will be updated to build 19044.6456.
Windows 10 users can also download and install the KB5066791 update manually Microsoft Update Catalog,
What’s new in Windows 10 KB5066791?
Windows 10 has officially reached end of support today, no longer receiving updates unless customers and organizations subscribe to extended security updates.
“After October 14, 2025, Microsoft will no longer provide free software updates, technical support, or security fixes for Windows 10 from Windows Update,” Microsoft warns.
“Your PC will still work, but we recommend moving to Windows 11.”
Consumers can enroll in Extended Security Updates to receive one year of additional security updates, while enterprises can purchase up to three years of Extended Updates.
However, Windows 10 users in EMEA are able to get free extended security updates for one year.
The full list of changes and improvements in the Windows 10 KB5066791 update is listed below:
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(input and structure)
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Solution: An issue with the Chinese input method editor (IME). Private Unicode characters were shown incorrectly and did not meet the GB18030 standard.
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Fix: Fixed an issue that affected USER32 edit controls. Surrogate pairs appear as empty boxes when text fields reach their length limit.
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(Windows Remote Management (WinRM))
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(licensing)
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New! This update introduces a servicing stack update (SSU) that includes an updated certificate chain to improve Azure environment validation. For more information see servicing stack update Section.
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(fax modem driver)
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(SMBv1 protocol connectivity (known issue)) Fixed: An issue where you would not be able to connect to shared files and folders if you are using the Server Message Block (SMB) v1 protocol over TCP/IP NetBIOS.netbtThis can happen after installing updates KB5065429,
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(Autopilot Enrollment Status Page (ESP) (Known Issues)) Fixed: A problem while using windows autopilot To deploy Windows 10, version 22H2 on devices with Enrollment Status Page (ESP) Configured it may be found that ESP does not load during out-of-box experience (OOBE).
The full list of improvements can be found here KB5066791 Support Bulletin and last month KB5066198 Preview Update Bulletin,
Microsoft says there are no known issues with this update as Microsoft has ended its support for the operating system.
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