There's a particular kind of frustration that comes from watching Windows Update fail at the very end of a download. The progress bar fills. You relax. Then the message appears: "We couldn't install this update — KB5070773." You hit Retry. Thirty minutes later, the same wall. If that loop describes your week, the phrase kb5070773 26200.6901 failed to install is probably already sitting in your search history.
Here's the first thing I want you to know: this isn't a sign that your PC is dying. KB5070773 is a 2025 out-of-band update, released on October 20, to repair a Windows Recovery Environment (WinRE) damaged by the earlier KB5066835 security update. Because it reaches into parts of Windows that ordinary cumulative updates don't touch, the standard "try again" approach often fails. In this guide, I'll walk you through the fixes that actually work, ordered from the most successful community-verified repair to the most reliable last resort.
Why Windows 11 KB5070773 Not Installing? Start With the WinRE Root Cause
If you've been treating KB5070773 like a normal monthly update, you've been fighting the wrong battle. Most cumulative updates layer new code on top of a healthy system. KB5070773 does something more delicate: it repairs the recovery environment itself. And when the thing being repaired is the thing that's broken, Windows Update can get stuck in a loop.
KB5066835 Broke WinRE, Making KB5070773 an Unusual Update
Let me lay out the chain of events, because it explains everything.
On October 14, 2025, Microsoft shipped KB5066835 as part of Patch Tuesday. It was supposed to be routine. Instead, testers — including the team at Windows Latest, which runs updates across dozens of configurations — found a nasty side effect: USB keyboards and mice stopped working inside WinRE. Think about what that means. The recovery environment is the screen you get when Windows crashes, when you hit a Blue Screen of Death, when you need to reset your PC or boot from a USB drive. If you can't click or type there, the recovery tools become decoration.
Microsoft was able to reverse some KB5066835 problems server-side. This one couldn't be fixed that way. So on October 20, KB5070773 went out as an out-of-band update. The Microsoft release notes confirm the fix: "USB devices, such as keyboards and mice, do not function in the Windows Recovery Environment (WinRE). This issue prevents navigation of any of the recovery options within WinRE."
Here's where the build numbers matter. If you're on Windows 11 25H2, KB5070773 moves you to OS Build 26200.6901. If you're on 24H2, it moves you to 26100.6901. Before the update, both versions were sitting at .6899 — the build attached to KB5066835. That difference of two digits is the entire story: this update exists to undo the damage caused by the previous one.
One more scenario worth naming. If you're already stuck inside WinRE with no working input, don't panic. Try a touchscreen if your device has one. Try a PS/2 keyboard if you have an older port. Or boot from a USB recovery drive created on a machine that's still working.
Read the Windows Update Error Code Before Fixing KB5070773 Failed to Install
Before you start running repair commands, take thirty seconds to find out exactly what Windows Update is complaining about. The code on your screen isn't the whole diagnosis, but it's a useful starting point.
Which Error Code Did Windows Update Show?
Open Settings > Windows Update > Update history. You'll see the failed KB5070773 entry, and beneath it, the error code. Write it down. Screenshot it if you're worried about forgetting it.
Three codes show up most often with KB5070773:
| Error code | What it typically signals |
|---|---|
| 0x800f0983 | The update package couldn't be applied to the component store |
| 0x800f0991 | A servicing operation failed — often another component store symptom |
| 0x80070306 | A less specific failure that frequently appears when update services stall or the download cache is corrupted |
| I want to be honest with you about what these codes do not tell you. They don't tell you which repair will work. In the support threads I've followed for this update, users with the same code have succeeded with different fixes, and users with different codes have sometimes succeeded with the same one. That's why the repair ladder below is designed to work for all three. The order matters more than the code. |
Fix KB5070773 26200.6901 Failed to Install With Windows Update Recovery Reinstall Now
Let's start with the fix that has the highest success rate, according to the community reports I've seen. It's hidden inside Windows' own recovery tools, and most people never realize it exists.
The Highest-Success First Fix: Use Windows Update to Repair Windows
Go to Settings > System > Recovery. Look for the section labeled Fix problems using Windows Update. Click Reinstall Now.
Yes, it sounds like it will wipe your system. It won't. This option reinstalls the current version of Windows on top of itself, keeping your personal files, installed applications, and most settings intact. What it repairs is the underlying system state — including the component store that Windows Update depends on.
I first used this feature years ago on a machine that had failed every manual repair I attempted. I was skeptical. It took about half an hour, and when it finished, the machine was healthy. For KB5070773 specifically, I've seen this same outcome confirmed in a Microsoft Q&A thread and echoed in multiple Reddit conversations about WinRE-related update failures.
Before you start, plug the device in. Set aside 20 to 40 minutes. The screen may appear frozen at various points — that's normal. Do not interrupt the process. When it finishes, your PC will restart, and you can check Windows Update again. In many cases, KB5070773 will install cleanly on the first attempt afterward.
Run DISM and System File Checker When KB5070773 Failed to Install
If the Windows Update recovery option didn't do the job, the next step is to repair the component store manually. This is where the command line becomes your friend.
Command-Line Repair for Corrupted System Files
Right-click the Start button and choose Terminal (Admin) or Command Prompt (Admin). Then run these two commands in order:
DISM /Online /Cleanup-Image /RestoreHealth
SFC /scannow
The first command repairs the component store — the same store Windows Update needs to install KB5070773. The second one, System File Checker, scans protected system files and replaces any corrupted ones with the correct versions.
Here's what to expect: DISM takes a while. On one of my older test laptops, it ran for nearly fifteen minutes, and the progress bar seemed stuck at 62% for an eternity. That's normal. Let it finish. When it completes, you may see a message saying the repair operation was completed, or that it couldn't fix everything. Either way, run SFC next.
If DISM repaired files during the first pass, reboot and run SFC /scannow again. This second pass matters more than people think — DISM can fix the underlying store, but SFC needs a clean run to catch everything else.
When both commands report no problems, return to Windows Update and try KB5070773 once more.
Reset Windows Update Components and SoftwareDistribution Folder After KB5070773 Failed to Install
There's a specific failure pattern that none of the previous fixes address: the update downloads to 100%, then fails during installation. Every single time. If that's what you're seeing, the update cache itself is probably corrupted.
Safely Clear a Corrupted Windows Update Cache
This procedure is well-known in Windows troubleshooting circles, but it needs to be done carefully. Open an elevated Command Prompt and stop four services:
net stop wuauserv
net stop bits
net stop cryptSvc
net stop msiserver
Those are, respectively, Windows Update, Background Intelligent Transfer Service, Cryptographic Services, and the Windows Installer. Now rename the two folders where Windows stores update data:
ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 catroot2.old
I want to emphasize the word rename. Do not delete these folders. Renaming them to .old lets Windows create fresh versions while keeping a fallback if something goes wrong. After the rename, restart the services:
net start wuauserv
net start bits
net start cryptSvc
net start msiserver
Reboot, then open Windows Update again. The fresh cache forces a complete re-download, which often clears the stuck-at-100% failure mode.
One quick note: you don't need a third-party "Windows Update Reset" tool for this. The built-in commands do exactly the same thing without the bundled adware risk.
Download KB5070773 Standalone Installer From Microsoft Update Catalog
If Windows Update itself is the problem — not your system, but the service — then the fix is to bypass it entirely. Microsoft publishes every update as a standalone package in the Microsoft Update Catalog.
Choose the Correct Package: OS Build 26200.6901 or 26100.6901
Before you download anything, press Windows key + R, type winver, and press Enter. Note the version and build number shown.
| Your version | Target build after KB5070773 | KB5070773 package to select |
|---|---|---|
| Windows 11 25H2 (build 26200.x) | 26200.6901 | Choose the entry for version 25H2 |
| Windows 11 24H2 (build 26100.x) | 26100.6901 | Choose the entry for version 24H2 |
| Go to the official Microsoft Update Catalog and search for KB5070773. You'll see separate entries for 24H2 and 25H2, plus x64 and ARM64 variants. Pick the one that matches your edition and architecture. |
This is the part where people get confused, so pay attention: the catalog download often lists two files. The first is the KB5070773 cumulative update. The second is a servicing stack update (SSU) — for this release, that's KB5067360. The SSU is a prerequisite. In most cases, your system already has it, particularly if you've been receiving updates regularly. If you see a servicing stack error during installation, install the SSU first, then the main update.
Once downloaded, double-click the .msu file, or run it from an elevated command prompt with wusa.exe C:\path\to\file.msu. The installation may take ten to twenty minutes.
Standalone Installer vs Windows Update: Which Should You Use?
My general rule: use Windows Update first, because it automatically handles prerequisites and servicing stack dependencies. You don't have to think about which file goes before which.
Use the standalone installer in three situations: when Windows Update repeatedly fails at the same point, when the update doesn't show up in Settings at all, or when you need to update multiple machines offline.
But here's the honest limitation. The standalone installer is a targeted fix. It does not repair underlying component store corruption. If your system files are damaged — which is common with this particular update — the .msu will fail the same way Windows Update failed. That's why the DISM and SFC steps come first. If you've already run them and still see failures, the standalone installer is the logical next move.
Run an In-Place Upgrade When Windows 11 KB5070773 Still Not Installing
This is the last resort, and it sounds more intimidating than it is.
Repair Install With a Current Windows 11 ISO
Download a Windows 11 ISO from Microsoft's official download page. Make sure it's a current image — ideally one released after October 20, 2025, so the KB5070773 fix is already baked into the recovery environment.
Mount the ISO by right-clicking it and choosing Mount. Then run setup.exe from inside the mounted drive. Windows Setup will ask how you want to proceed. Choose Keep personal files and apps. This is a repair installation, or in-place upgrade, and it replaces Windows system files while leaving your data and applications alone.
I've walked several people through this process, and the fear is always the same: "What if it wipes everything?" The first time I ran a repair install myself, I spent the entire hour waiting for something to break. Nothing did.
Still, back up your important files first. The repair install is designed to preserve everything, but "designed to" isn't the same as "guaranteed." A few minutes of backup saves you a world of regret if something unusual happens.
After the process completes, open Windows Update. The repair install resets the component store, clears most update blocks, and gives KB5070773 a clean base to work with.
Verify the Fix and Confirm WinRE Works After KB5070773 Failed to Install
Once the update finally installs, don't just close the Settings window and move on. Take two minutes to confirm everything actually worked.
Confirm the Correct OS Build and Recovery Environment Status
First, press Windows key + R, type winver, and check the build. It should read 26200.6901 on Windows 11 25H2, or 26100.6901 on 24H2. If it does, KB5070773 is on your system.
Second, go to Settings > Windows Update > Update history. You should see KB5070773 listed as successfully installed on the current date.
Third — and this is the step most guides forget — verify that the Windows Recovery Environment is still enabled. Open an elevated Command Prompt and run:
reagentc /info
Look for the line that says Windows Recovery Environment. It should read Enabled. If it says Disabled, you can re-enable it with reagentc /enable.
If you want a full functional check, restart your PC and boot into Advanced Startup (Settings > System > Recovery > Advanced startup). Once you're in WinRE, move your mouse and type a few characters. If both work, the original problem is solved, not just the update.
FAQ
Why does KB5070773 fail to install on Windows 11?
KB5070773 is unusual because it's not a standard feature or security update. It's an out-of-band repair for the Windows Recovery Environment, which was damaged by the preceding KB5066835 update. When the recovery environment or the component store is already corrupted, Windows Update often can't install a fix that depends on those very components. That's why the error appears repeatedly, and why ordinary retries don't help.
What does Windows Update error 26200.6901 mean?
It doesn't mean anything — because it isn't an error code. 26200.6901 is the target OS build number for Windows 11 25H2 after KB5070773 is installed. If you see "26200.6901" associated with a failure, look for the actual Windows Update error code, such as 0x800f0983, 0x800f0991, or 0x80070306. Those codes will help you choose the right fix.
How do I fix KB5070773 not installing?
Start with Settings > System > Recovery > Fix problems using Windows Update, then choose Reinstall Now. Windows will repair itself and keep your files; expect it to take 20 to 40 minutes. If that fails, run DISM /Online /Cleanup-Image /RestoreHealth followed by SFC /scannow from an elevated command prompt. Then reset the Windows Update components by stopping the related services and renaming the SoftwareDistribution and catroot2 folders. If nothing else works, download the standalone installer from the Microsoft Update Catalog, matching the package to your Windows version and build.
Can I skip KB5070773 if it keeps failing to install?
You can, but I'd advise against it. This update repairs a real problem — the keyboard and mouse don't work inside the Windows Recovery Environment after KB5066835. If you ever hit a serious system failure, you'll be trying to recover a PC you can't navigate. The November 2025 Patch Tuesday update is expected to include the same fix, so skipping it isn't catastrophic, but the safer path is resolving the installation now rather than hoping you never need WinRE.
Conclusion
Seeing kb5070773 26200.6901 failed to install in Windows Update is frustrating, but the situation makes more sense once you understand what this update actually is: a repair for a recovery environment that a previous update broke. That unusual purpose explains why the normal fixes don't work and why component store damage can block the installation entirely.
Work through the repairs in order. Try the Windows Update recovery option first — it has the highest success rate and the lowest risk. If that doesn't work, run DISM and SFC to repair the component store. Reset the update cache if downloads stall at 100%. Then move to the Microsoft Update Catalog standalone installer, and finally to an in-place upgrade if nothing else succeeds.
After the update lands, verify the OS build and check reagentc /info to confirm the recovery environment is enabled. Don't leave WinRE broken — it's the tool you'll need on the worst day your PC has. Start with Settings > System > Recovery > Fix problems using Windows Update and choose Reinstall Now. If that doesn't crack the KB5070773 failure, bookmark this guide and work down the ladder.