Fix Error 0x8007043c 0x90018: Windows Update

Error 0x8007043c 0x90018 appears during Windows Update or Microsoft Store downloads and means the update service couldn’t complete an operation, usually because of a permissions or service conflict. The fix is to reset the Windows Update components and clear the SoftwareDistribution folder, which resolves the issue in most cases. Below is a step-by-step guide, plus background on why this error occurs and what to do if the basic fix doesn’t work.

What This Error Means

The hexadecimal code 0x8007043c translates to ERROR_SUCCESS_REBOOT_REQUIRED, meaning the system needs a restart to finish a previous operation. The second part, 0x90018, is a Windows Update-specific code that often indicates the update service (wuauserv) is in a bad state or the update cache is corrupted. Together, they usually surface when Windows tries to install a new update but a pending reboot, a stopped service, or a locked file blocks it.

You might see this error in the Windows Update settings page, in the Microsoft Store, or in the WindowsUpdate.log file. It’s not a hardware problem and doesn’t indicate a failing drive or RAM. It’s almost always a software state issue that can be cleared without reinstalling Windows.

Why It Happens: Common Causes

The error typically appears because of one or more of these conditions:

A previous update or driver install left the system in a “reboot pending” state that wasn’t cleared properly.
The Windows Update service (wuauserv), Background Intelligent Transfer Service (BITS), or Cryptographic Services (CryptSvc) is stopped or disabled.
The SoftwareDistribution folder, where Windows stores downloaded updates, contains corrupted or locked temporary files.
Third-party antivirus or system optimization tools interfere with the update process.
Insufficient disk space on the system drive (C:) prevents new update files from being written.

Less commonly, the error can appear after a failed feature update (like a Windows 11 version upgrade) where the old installation files weren’t cleaned up.

Step-by-Step Fix: Reset Windows Update Components

Follow these steps in order. You’ll need an administrator account. If you’re not sure if your account has admin rights, check Settings > Accounts > Your Info—if it says “Administrator,” you’re set.

Press Windows + R, type services.msc, and press Enter.
Find the following services, right-click each, and select Stop (if they’re running): Windows Update, Background Intelligent Transfer Service (BITS), Cryptographic Services, and Windows Installer.
Open File Explorer and navigate to C:\Windows\SoftwareDistribution. Rename this folder to SoftwareDistribution.old (right-click > Rename). If you get an error that the folder is in use, make sure the services above are stopped and try again.
Also rename C:\Windows\System32\catroot2 to catroot2.old (this is the catalog for signed drivers and updates).
Go back to the Services window, right-click each service you stopped, and select Start.
Restart your PC, then try Windows Update again.

If renaming the folders fails because of permissions, you can use the Command Prompt as an administrator:

Press Windows + X and select Terminal (Admin) or Command Prompt (Admin).
Type the following commands one at a time, pressing Enter after each: net stop wuauserv, net stop bits, net stop cryptsvc.
Then type ren C:\Windows\SoftwareDistribution SoftwareDistribution.old and ren C:\Windows\System32\catroot2 catroot2.old.
Finally, restart the services: net start wuauserv, net start bits, net start cryptsvc.

If the Basic Fix Doesn’t Work

Sometimes the error persists because of a deeper issue. Try these in order:

Run the Windows Update Troubleshooter: Go to Settings > System > Troubleshoot > Other troubleshooters, select Windows Update, and run it. This automates many of the steps above and also checks for pending reboots.
Check for pending reboot: Open Registry Editor (regedit) and navigate to HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Component Based Servicing\RebootPending. If this key exists, restart your PC a couple of times to clear it.
Free up disk space: Windows Update needs at least 10-20 GB free on the system drive for feature updates. Use Disk Cleanup (cleanmgr) to remove temporary files.
Run DISM and SFC: Open Command Prompt as admin and run DISM /Online /Cleanup-Image /RestoreHealth, then sfc /scannow. This repairs corrupted system files that might be causing the error.
Boot into Safe Mode: If third-party software is interfering, booting into Safe Mode (with Networking) and then running Windows Update can bypass it. To enter Safe Mode, hold Shift while clicking Restart in the Start menu, then choose Troubleshoot > Advanced Options > Startup Settings > Restart, and press 5.

Preventing This Error in the Future

Most users see this error after a forced shutdown or a failed update. To reduce the chance of recurrence:

Always let Windows finish updates before shutting down—don’t force power off during the “Working on updates” screen.
Keep at least 15-20 GB free on your system drive.
Avoid using “registry cleaner” or “PC optimizer” tools that modify Windows Update services.
If you use third-party antivirus, check its settings to ensure it isn’t blocking Windows Update (some have a “game mode” that suspends background services).

Common Misconception: It’s a Virus or Hardware Failure

Many users panic when they see a hex error code, assuming malware or a dying hard drive. Error 0x8007043c 0x90018 is not a virus indicator, and it doesn’t correlate with disk health. It’s a service communication failure. Running a full antivirus scan or checking SMART status is fine, but it’s unlikely to be the cause. The fix is almost always in the update components themselves.

When to Consider a Repair Install

If you’ve tried all the above and the error still appears, a repair install (in-place upgrade) can fix it without losing your files or apps. Download the Windows 11 Installation Assistant or the Media Creation Tool from Microsoft’s official site, run it, and choose “Keep personal files and apps.” This reinstalls the OS while preserving your data. It’s a last resort but very effective for persistent update corruption.

Note: This error is not related to the 0x8007043c error that can appear when ejecting a USB drive (which is a different issue about device removal). The context—Windows Update or Store—is what matters.

Frequently Asked Questions

Will I lose my files if I rename the SoftwareDistribution folder?

No. That folder only contains downloaded update files and update history logs. Windows will recreate it automatically the next time you run an update. Your personal documents, photos, and installed programs are untouched.

Why does the error mention a reboot if I already restarted?

Windows sometimes marks a reboot as pending in the registry even after a restart, especially if a previous update was interrupted. The Component Based Servicing (CBS) key can get stuck. Running the DISM command usually clears that state.

Can I just disable Windows Update to avoid this?

You can pause updates for up to 5 weeks in Settings, but permanently disabling them is not recommended—you’ll miss security patches. If you must delay, use the “Pause updates” option rather than stopping the service manually.

Is this error related to the Microsoft Store?

Yes, the Microsoft Store uses the same underlying update services. If you see this error in the Store, the same fix applies—reset the update components. After that, open the Store, click Library, and try downloading again.

How long does the fix take?

The manual reset takes about 5-10 minutes, plus a restart. The DISM and SFC scans can take 15-30 minutes depending on your drive speed. The repair install takes about an hour but is usually only needed if nothing else works.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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