Windows 11 Build 26220.9587 Beta Adds Cloud Rebuild Shortcut and Unicode 17.0 Support

Where this build sits in the Beta Channel​

Microsoft says Beta Channel updates are still based on Windows 11, version 25H2, delivered through an enablement package. That has been the pattern for the whole 26220 branch. Microsoft's earlier Beta release notes, such as those for Build 26220.8575, carry the same reminder that updates are based on Windows 11, version 25H2 via an enablement package.

Microsoft's KB5054156 documentation explains the enablement-package model. Versions 24H2 and 25H2 share a common core OS with identical system files, and 25H2 features sit dormant until a small "master switch" package turns them on, which takes one restart.

This build comes less than a week after the last Beta flight. Windows Report noted that Microsoft has released Windows 11 Insider Preview Build 26220.9568 to the Beta Channel, with changes to accessibility, Phone Link, Magnifier and File Explorer. Its headline feature was Pointer Indicator, a new accessibility feature designed to make the mouse cursor easier to locate, especially for users with low vision. Compared with that, .9587 is a maintenance-style flight.

Section summary: Build 26220.9587 is a small 25H2-based Beta update that follows the feature-heavier .9568 release by about a week.

Unicode 17.0 text shaping: a bigger job than it sounds​

Microsoft says it updated Windows text-shaping support for Unicode 17.0 so that Windows can correctly display and shape newly encoded characters and scripts. The notes highlight four new scripts: Beria Erfe, Sidetic, Tai Yo and Tolong Siki.

The Unicode Consortium's Version 17.0 summary confirms the numbers. Unicode 17.0 adds 4,803 characters, bringing the total to 159,801, and the four scripts are its new scripts. Most of the 4,803 characters are not in those four scripts. The Consortium says the new CJK Unified Ideographs Extension J block alone contains 4,298 ideographs, which pushes the number of CJK ideographs past 100,000.

The Consortium's migration notes also explain why Microsoft talks about shaping and not just "support":

• Tai Yo has complex layout. Unicode singles it out as the one new script needing complex layout. Assigning code points is the easy part. Glyphs only form correctly if the shaping engine knows the script's rules.
• Tolong Siki brings its own decimal digits. Unicode warns that software dealing with numeric values and number formatting needs to account for this new digit set.
• Line-breaking changed too. Unicode 17.0 adds a new Line_Break property value, Unambiguous_Hyphen, which grew out of problems handling hyphens in Hebrew.

Keep expectations realistic. Shaping in the operating system is only one piece. Text in a new script still needs a font that contains the glyphs, an app that uses the system shaping stack, and usually an input method. Microsoft's note does not name specific fonts, APIs, apps or keyboard layouts, so don't assume you can type Sidetic in Notepad tonight.

Developers who handle multilingual text should test their rendering code against this build. Pay particular attention to Tai Yo layout and to any code that parses numbers, which may meet the Tolong Siki digits.

Section summary: This is groundwork for scripts with small user communities. It matters most to developers and localization teams, and real-world use still depends on fonts and apps catching up.

Settings home page: faster, with a caveat​

Microsoft says it made performance improvements to the Settings home page that "should result in reduced loading times in certain scenarios." That is a qualified claim. Microsoft gives no benchmarks, does not say which scenarios improve, and does not say whether every device benefits.

If you've ever clicked Settings and waited for the home page cards to fill in, this is aimed at you. Until Microsoft publishes numbers or Insiders report results in Feedback Hub, though, it's a promised improvement, not a measured one.

Cloud Rebuild gets a front door in Settings​

This is the change most worth understanding. The build adds an entry point for Cloud Rebuild under Settings > System > Recovery to make the feature easier to reach. The notes do not say this build introduces or changes Cloud Rebuild itself. It is a new way to get to it.

What Cloud Rebuild actually does​

Microsoft's Cloud Rebuild documentation, which is labeled preview, describes it as a full operating system reinstall:

• It differs from Reset this PC because it downloads both the Windows image and the device's drivers from Windows Update. That means no USB media, no custom image, and no reliance on the installed OS being healthy.
• It reformats the system disk and removes all locally stored files, accounts, apps and settings. Data in cloud services such as OneDrive is not affected.
• After the rebuild, the PC boots into the out-of-box experience (OOBE). Devices that are Microsoft Entra-joined, managed by Intune and registered with Autopilot can re-provision automatically.
• Microsoft says the preview should be used only on non-production devices.

So this new Settings shortcut leads to a full wipe and reinstall, not a quick repair. Confirm your backups before you click it.

Prerequisites from Microsoft's documentation​

1. The device runs Windows 11 and has a healthy Windows Recovery Environment. Run reagentc /info from an elevated command prompt to confirm WinRE is enabled.
2. The manufacturer has included a compatible networking driver in WinRE, and the device can reach the internet from WinRE.
3. The device meets the Windows 11 minimum hardware requirements.

The documented flow​

Before this build, Microsoft documented the route as Settings > System > Recovery > Restart now next to Advanced startup, then Troubleshoot > Cloud rebuild in WinRE. From there:

1. Ethernet connects automatically. On Wi-Fi, you choose a WPA-Personal network and enter the passkey.
2. Cloud Rebuild contacts Windows Update to work out the target build and download networking drivers.
3. You choose Remove files, which is faster but leaves files that specialized tools may be able to recover, or Remove & sanitize files, which is slower and meant for PCs being recycled, returned or reassigned.
4. You check that the target build, edition and language are what you expect, acknowledge the data-loss warning, and continue.
5. You keep the device on power and don't interrupt it. Microsoft warns that an interrupted rebuild can leave Windows unable to boot.

The release notes do not say exactly how the new Settings entry hands off to this flow, so we won't guess.

Troubleshooting common failures​

Microsoft documents three error codes worth knowing:

For bug reports, Microsoft says to copy logs from X:\$Windows.~BT\Sources\Panther and X:\Windows\Logs\Rebuild using the WinRE Command Prompt, then file them in Feedback Hub under the Cloud rebuild category.

On the sanitize option, Microsoft notes that the result depends on the storage hardware. Windows asks the drive to erase itself and reports what the drive says it did, but it can't verify that independently. If you have regulatory obligations, check with the manufacturer.

For IT admins​

Cloud Rebuild can also be triggered remotely through the Recovery CSP, using nodes under ./Device/Vendor/MSFT/Recovery/CloudRebuild. These include EnableLocalRebuild, EnableCustomRebuild and an Execute subtree. Microsoft says these nodes exist only in Insider builds and may change. The new Settings entry is a convenience for local users. Nothing in the notes says it changes policy behavior or which devices qualify. If you have Insider test devices in an Intune pilot, check whether you have blocked local rebuilds. When EnableLocalRebuild is disabled, the documentation says users who try to start a rebuild get an error page.

Section summary: Moving Cloud Rebuild into Settings makes a strong recovery tool easier to find. Easier to find also means easier for a curious user to start a full wipe, so the data-loss warning is the main safeguard.

Should you install it?​

If you're already in the Beta Channel, this build is low-risk and fairly uneventful. Microsoft's usual reminders apply:

• Features may change, be removed, or never ship outside the Insider program.
• Some features may not be fully localized yet. Report localization problems in Feedback Hub.
• The watermark in the lower-right corner of the desktop is expected on pre-release builds.
• Flight Hub lists which build is in which channel.

Bottom line: Build 26220.9587 adds Unicode 17.0 shaping support for developers and localization teams, a claimed but unmeasured Settings speedup, and a Settings entry point for a recovery tool that erases the PC. If you're testing Cloud Rebuild, check WinRE with reagentc /info, make sure the device can reach the network from WinRE, and back up before you start.