How to fix Windows update error 0x800f0993?

Install error 0x800f0993 means the part of Windows that installs updates could not find the files it needs to build the new versions of system files. It appears on Windows 11 24H2 and 25H2 with the monthly cumulative update, most often on PCs that were upgraded from an older Windows. Restart the PC and check for updates again first.

Facts checked on 14 October 2026. Steps written for Windows 11 (24H2, 25H2 and 26H2).

What install error 0x800f0993 means

0x800f0993 is an error of the Windows servicing stack, the component that installs updates. It is not a download error and not a network error. The update arrived on the PC in full, and the installation failed while Windows was putting the new files together.

Microsoft's public list of common Windows Update errors does not include this code. The name comes from Microsoft's service alert of June 2026, which BleepingComputer quoted: in the Windows Update log files the code is PSFX_E_REBASE_HYDRATION_CANDIDATES_MISSING. Read plainly, Windows was rebuilding files from small differences and the files to build from were not there.

The picture shows why this code belongs to Windows 11 24H2 and later. Microsoft Learn explains that monthly updates are delivered as binary differences, and that since 24H2 they are computed against a checkpoint cumulative update. The first checkpoint is KB5043080 of 10 September 2024, OS build 26100.1742.

Why Windows update error 0x800f0993 appears

One cause is confirmed by Microsoft. The others come from Microsoft's documentation of how the updates are built and from what analysts found in users' logs. They are ordered from the most likely to the least likely.

The first row is Microsoft's own statement of 9 June 2026. According to BleepingComputer, Microsoft wrote that a small percentage of devices upgraded this way "might fail to install the latest cumulative update", and that Update history shows "error 0x80073712/0x800f0993". Microsoft said that no new devices should be affected from 19 May 2026.

The second row is a report, not a Microsoft statement. In a Sysnative thread about KB5079473 failing with 0x800F0993, an update analyst read the user's CBS log and found a Polish language pack that was partly installed with many files missing. Microsoft's checkpoint article explains why that matters: language packs and features on demand need the full content of every checkpoint.

Where CBS.log and the Windows Update logs are, and what to look for

You do not need the logs for Fix 1 and Fix 2. Read them when those two did not help, because the log names the package or the file that is missing, and that tells you whether Fix 3, Fix 4 or Fix 5 is yours.

1. Press Win + R, type %systemroot%\Logs\CBS and press Enter.
2. Copy CBS.log to the Desktop and open the copy in Notepad, so that the original stays untouched.
3. Press Ctrl + F and search for 0x800f0993. Note the date and time of the last hit.
4. Search for , error and go to the lines with the same time. This is the search Microsoft gives for reading CBS.log.
5. Read ten to twenty lines above the error line. Look for a package name that contains a language code such as pl-PL, a name with RollupFix, or a file path under WinSxS.

Windows Update itself no longer writes a readable text log. It writes trace files, and Get-WindowsUpdateLog merges them into WindowsUpdate.log on the Desktop of the current user. Microsoft notes that this file is a static copy: run the command again after a new failed attempt.

• A language code in the failing package name points to Fix 3.
• RollupFix with the version 26100.1742.1.10 points to Fix 2.
• A missing file under WinSxS or the name ERROR_SXS_COMPONENT_STORE_CORRUPT points to Fix 5, then Fix 8.
• No clear name at all: go through the fixes in order.

How to fix Windows update error 0x800f0993

Fix 1 to Fix 3 are specific to this code and take minutes. Fix 4 installs the update around Windows Update, with its checkpoint. Fix 5 to Fix 7 are the general repairs. Fix 8 reinstalls Windows over itself and keeps your apps and files: it is the one Microsoft names when nothing else works.

Fix 1. Restart the PC and check for updates again

5 to 20 minutesNo riskAlways first, and above all on a Home PC that was upgraded to Windows 11 24H2 or 25H2.

For the known issue of June 2026 Microsoft said the fix reaches Home PCs and unmanaged business PCs after a restart, and that restarting "might allow the resolution to apply sooner". A newer cumulative update can also replace the one that failed.

1. Save your work and select Start > Power > Restart. Use Restart, not Shut down.
2. Open Settings > Windows Update and select Check for updates.
3. Install everything that is offered. If the failed update is still listed, select Retry next to it.
4. If it fails again, restart once more and repeat the check one time.
5. Open Settings > Windows Update > Update history and read whether the update is now listed as installed.

Microsoft's wording, as quoted by BleepingComputer, was: "No other action is required beyond a device restart." That sentence covers Home PCs and business PCs that are not managed. It does not cover PCs that get updates from a company server.

Fix 2. Remove the leftover update package on an upgraded PC

10 to 20 minutesRead the warningThe PC was upgraded to Windows 11 24H2 or 25H2 from Windows 10 or from Windows 11 23H2, and Fix 1 did not help.

Microsoft said the known issue is not repaired on PCs that were already upgraded. For those, BleepingComputer quotes Microsoft's alert: remove the affected package with one DISM command to unblock update installation. The package is the September 2024 checkpoint, version 26100.1742.

1. Right-click Start and select Terminal (Admin). Select Yes when Windows asks for permission.
2. List the cumulative update packages on the PC:

   dism /online /get-packages /format:table | findstr /i RollupFix

3. Look for a line with Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.1742.1.10. If it is not in the list, stop here and go to Fix 3.
4. If it is listed, remove it with the command from Microsoft's alert:

   dism /online /remove-package /packagename:Package_for_RollupFix~31bf3856ad364e35~amd64~~26100.1742.1.10

5. Wait until DISM says The operation completed successfully. and restart the PC when it asks.
6. Open Settings > Windows Update and select Check for updates.

Microsoft's alert is published in the Microsoft 365 admin center, which needs a business account, so we read it through BleepingComputer's report of 10 June 2026. The syntax of /Get-Packages and /Remove-Package is from Microsoft Learn.

Fix 3. Remove language packs you do not use

10 minutesLow riskYou have more than one display language, or you once started to add a language and it did not finish.

A cumulative update also updates every installed language pack. Microsoft's checkpoint article says language packs need the full content of all checkpoints, so a pack that is only partly installed has nothing to build on. In a Sysnative case this was the cause found in the CBS log.

1. Open Settings > Time & language > Language & region.
2. Read the list in the Language section. Every language there has files that the update must service.
3. Next to a language you do not use, select the three dots and then Remove. Confirm with Yes.
4. Repeat for every other language you do not need. Keep your Windows display language.
5. Restart the PC.
6. Open Settings > Windows Update and select Check for updates.

In the Sysnative thread, removing the language in Settings was not enough for one user, and the analyst removed the leftover parts with PowerShell on that PC. Those commands were written for one machine from its logs, so we do not repeat them here. If the CBS log still names a language after this fix, go to Fix 8.

Fix 4. Install the update by hand with its checkpoint update

20 to 40 minutesLow riskOne cumulative update keeps failing, or the build number in winver is below 26100.1742.

The Microsoft Update Catalog gives the full package and the checkpoint it depends on. Microsoft's pages for KB5121003 and KB5129195 say the update needs MSU files installed in a specific order, and that DISM finds and installs the checkpoint when all files are in one folder.

1. Check your Windows version. Press Windows key + R, type winver and press Enter. Note the version (for example 25H2) and the OS build.
2. Find the KB number. Open Settings > Windows Update. A failed or pending update is listed with its KB number; earlier ones are under Update history.
3. Check the processor type. Open Settings > System > About and look at System type: an x64-based PC needs the x64 file, an ARM-based PC (for example Snapdragon) needs the arm64 file.
4. Search the catalog. Open the Microsoft Update Catalog at catalog.update.microsoft.com in your browser, type the KB number (for example KB5124010) in the search box and press Enter.
5. Pick the right row. Find the row whose title names your Windows version and your processor type (x64-based or arm64-based) and select Download on that row.
6. Download every file listed. A window lists one or more .msu links. Download all of them into one empty folder, for example C:\packages. On Windows 11 24H2 and later the list can include earlier checkpoint updates that the new one needs.
7. Install a single file. If there is only one file, double-click it and confirm the installation in the Windows Update Standalone Installer.
8. Install several files with DISM. If there are several files, open an elevated Terminal or Command Prompt and run DISM with the newest file. DISM finds the other files in the same folder and installs them in the right order.

   DISM /Online /Add-Package /PackagePath:C:\packages\<newest-file>.msu

9. Restart. Restart the PC when the installation finishes, then run winver again: the OS build should have changed.

These steps were written for Windows 11 24H2 and later; Windows 10 22H2. The full page with the other versions and what each result means: Install an update from the Microsoft Update Catalog

Fix 5. Repair the component store with DISM and SFC

15 to 40 minutesNo riskUpdate history also shows 0x80073712, or the CBS log names missing files under WinSxS.

The companion code 0x80073712 means the component store is damaged, and Microsoft's answer for store damage is DISM with RestoreHealth followed by SFC. DISM downloads clean copies of the components that the update could not find.

1. Open an elevated command window. Right-click Start and select Terminal (Admin), or type cmd in the search box, right-click Command Prompt and select Run as administrator. Select Yes when Windows asks for permission.

   

2. Run DISM first. Type the command below and press Enter. DISM downloads clean copies of damaged components from Windows Update, so it can take several minutes. Wait until it says The operation completed successfully.

   DISM.exe /Online /Cleanup-Image /RestoreHealth

   

3. Run System File Checker. In the same window, type the command below and press Enter. Do not close the window until the verification reaches 100%.

   sfc /scannow

   

4. Read the result and restart. Compare the last message with the table below this guide, then restart the PC so that repaired files are loaded.

   

These steps were written for Windows 11 24H2 and 25H2. The full page with the other versions and what each result means: Run DISM and SFC to repair Windows system files

Fix 6. Run the Windows Update troubleshooter

5 minutesNo riskYou do not want to type commands, or the fixes above changed nothing.

The troubleshooter checks the update services and clears a stuck attempt. It cannot repair a missing package, and users on Microsoft's forum report that it found nothing for this code, but it is free of risk and rules out the simple cases.

1. Open Troubleshoot settings. Select Start > Settings > System > Troubleshoot.
2. Open the list of troubleshooters. Select Other troubleshooters.

   

3. Run the Windows Update troubleshooter. Under Most frequent, select Run next to Windows Update. The Get Help app opens and starts the checks.

   

4. Read the result. Wait until Get Help finishes. If it found and fixed a problem, it says so and asks whether this solved the problem. Answer the question so it can offer the next step.

   

5. Restart the PC. Restart when the troubleshooter finishes, even if it does not ask you to.
6. Check for updates again. Select Start > Settings > Windows Update > Check for updates, and install the updates it finds.

These steps were written for Windows 11 (screenshots: 26H2). The full page with the other versions and what each result means: Run the Windows Update troubleshooter

Fix 7. Reset the Windows Update components

10 minutesLow riskThe update fails at once at the same point, and the earlier fixes did not help.

A damaged download in the SoftwareDistribution folder is used again at every retry. Renaming the folder makes Windows download the update from scratch. It does not repair the component store, so it helps only when the downloaded files were the problem.

1. Open Command Prompt as administrator. Type cmd in the search box, right-click Command Prompt and select Run as administrator. Select Yes when Windows asks for permission.
2. Stop the update services. Type the commands below and press Enter after each one. If Windows says that other services depend on Cryptographic Services, it stops them too. A message that a service is not started is fine.

   net stop wuauserv
   net stop bits
   net stop cryptsvc

3. Delete the download queue files. This clears the list of downloads that the Background Intelligent Transfer Service keeps. If Windows says it cannot find the files, continue.

   del "%ALLUSERSPROFILE%\Application Data\Microsoft\Network\Downloader\qmgr*.dat"

4. Rename the update cache folders. Renaming keeps a copy in case you need it; Windows creates new, empty folders when the services start again. If you get Access is denied, a service is still running: repeat the previous step.

   ren %systemroot%\SoftwareDistribution SoftwareDistribution.old
   ren %systemroot%\System32\catroot2 catroot2.old

5. Start the services again. Type the commands below and press Enter after each one. The requested service has already been started is fine: Windows started it on its own.

   net start cryptsvc
   net start bits
   net start wuauserv

6. Restart and check for updates. Restart the PC. Then select Start > Settings > Windows Update > Check for updates. The first check can take longer than usual because everything is downloaded again.

These steps were written for Windows 11 and Windows 10 (the steps are the same). The full page with the other versions and what each result means: Reset Windows Update components

Fix 8. Reinstall Windows over itself with Fix problems using Windows Update

1 to 2 hoursLow riskNothing above worked, or the CBS log shows damage that DISM could not repair.

The reinstall replaces the system files and components with a clean copy of your current Windows version, so the missing base files are back. Microsoft says it keeps apps, files and settings. For the known issue, Microsoft advises an in-place upgrade when the DISM command does not help, and this is the built-in way to do one.

1. Open Recovery in Settings. Open Settings > System > Recovery. Next to Fix problems using Windows Update, select Reinstall now. This keeps your apps, files and settings.

   

2. Start the reinstall. Choose whether the PC may restart on its own 15 minutes after the installation, then select OK.
3. Wait and restart. Windows Update downloads and installs a repair copy of your current Windows version. Keep the PC plugged in and online, and restart it when asked.

These steps were written for Windows 11 22H2 and later. The full page with the other versions and what each result means: Reinstall Windows without losing files

• Keep the PC plugged in and online for the whole reinstall. Microsoft makes this a condition.
• Windows downloads a repair version of the last update that installed successfully, so the download is large.
• After the reinstall, open Settings > Windows Update and install the update that failed.

If error 0x800f0993 is still there

When the repair reinstall did not help or could not start, the choice depends on who manages the PC and on what the CBS log says.

• What to send to support: the exact code, the KB number, the OS build from winver, the date and time of the last failed attempt and CBS.log.
• Whether the PC was upgraded from Windows 10 or from Windows 11 23H2, and in which month.
• Which fixes you already ran, and the last line DISM printed.

How to keep error 0x800f0993 from coming back

If you plan to upgrade a Windows 10 PC to Windows 11, install every pending update on Windows 10 first. Microsoft's resolved update for Windows 10 22H2 and 21H2 is KB5094127, and it is meant to prevent this issue during the upgrade. Windows 10 itself left support on 14 October 2025.

Frequently asked questions

What does error 0x800f0993 mean?

It means the Windows servicing stack could not find the files it needs to build the new versions of system files while installing a cumulative update. In the Windows Update logs the code has the name PSFX_E_REBASE_HYDRATION_CANDIDATES_MISSING, as quoted from Microsoft's service alert of June 2026. The download is fine and your internet connection is not the cause. The fault is in the update base on the PC: a leftover package from an upgrade, a partly installed language pack, a missing checkpoint update or a damaged component store.

Why does KB5121003 fail with install error 0x800f0993?

KB5121003 is the security update of 11 August 2026 for Windows 11 24H2 and 25H2, OS builds 26100.9168 and 26200.9168. Microsoft's page for it lists other known issues, such as games that stop responding, but no install failure with 0x800f0993. The update fails because of the state of the PC, not because of its own content. That is why the same PC fails with the next month's update too. Start with a restart and a new check for updates, because a newer update has replaced KB5121003 by now.

Why does KB5129195 show 0x800f0993?

KB5129195 is an out-of-band update of 14 September 2026, OS builds 26100.9457 and 26200.9457, and since 29 September also 26300.9457 for Windows 11 26H2. Microsoft released it to fix Remote Desktop and Hyper-V problems of the September update. Its page does not list 0x800f0993 as a known issue. Like every cumulative update it needs the checkpoint update and an intact component store, and it fails with this code when one of them is missing. The fixes are the same as for any other KB.

Why can I not update to Windows 11 25H2 because of 0x800f0993?

Windows 11 24H2 and 25H2 receive the same cumulative updates: Microsoft's update pages list builds 26100 and 26200 together. So a PC whose cumulative updates fail with 0x800f0993 is stuck on both. Repair the update base first with Fix 1 and Fix 2. If the PC was upgraded from Windows 10 or from 23H2, it matches Microsoft's known issue of June 2026. When the fixes do not work, the repair reinstall in Fix 8 gives the PC a clean copy of Windows, after which updates install again.

Is 0x800f0993 a known issue that Microsoft will fix?

Partly. On 9 June 2026 Microsoft confirmed it for PCs upgraded to Windows 11 24H2 or 25H2 from Windows 10 22H2 or 21H2, or from Windows 11 23H2. For Home PCs and unmanaged business PCs the fix arrives after a restart. For managed devices Microsoft named resolved updates, KB5094126 for 24H2 and 25H2. According to BleepingComputer, Microsoft also said that PCs already upgraded are not repaired by those updates and need the DISM command in Fix 2. The issue is not on the public release health pages we read on 14 October 2026.

Do I lose my files if I use Reinstall now?

No. Microsoft's support page says that Fix problems using Windows Update reinstalls the same Windows version, repairs system files and components, and preserves your apps, files and settings. It is different from Reset this PC, which removes apps even when you choose Keep my files. Still, back up the files you cannot lose before any repair of Windows. Keep the PC plugged in and online for the whole process, and plan for an hour or more, because Windows downloads a full repair copy.

Does error 0x800f0993 appear on Windows 10?

We found no Microsoft statement about this code on a PC that still runs Windows 10. Windows 10 enters the story as the starting point: Microsoft's known issue covers PCs that ran Windows 10 22H2 or 21H2 and were then upgraded to Windows 11 24H2 or 25H2. The checkpoint updates that the code is tied to exist only since Windows 11 24H2. If you see the code on Windows 10, run DISM and SFC as in Fix 5. Windows 10 left support on 14 October 2025.

Where is CBS.log and what line do I look for?

CBS.log is in the folder %systemroot%\Logs\CBS, which on most PCs is C:\Windows\Logs\CBS. Copy the file to the Desktop and open the copy in Notepad. Search for 0x800f0993 to find the time of the failure, then search for the text Microsoft gives for this log: a comma, a space and the word error. The lines just above the error name the package or file that was missing. A language code in the name points to a language pack, and a path under WinSxS points to a damaged component store.

Is it safe to ignore the error and skip the update?

Not for long. The update that fails is the monthly cumulative update, which carries all security fixes for Windows. A PC with this error does not install the next month's update either, so it falls further behind every month. One or two weeks while you work through the fixes is fine. Leaving it for months is not, and on Windows 11 24H2 Home and Pro the October 2026 update is the last one, so the PC also has to move to 25H2.

Is this page the same answer for erro de instalação, error de instalación or Installationsfehler 0x800f0993?

Yes. The code is the same in every language of Windows: only the words in front of it are translated. Install error, erro de instalação, error de instalación, Installationsfehler and the other forms all stand for the servicing error described here, and the fixes are the same. The menu names in the steps are the English ones. In another display language, follow the position of the items: Settings, then Windows Update, then the button that checks for updates. The commands are typed in English on every PC.