[Solved] Fix 0xffff9401 Windows - 5 Minute Method

Verified & Tested Updated February 15, 2026

Quick Summary

The error code 0xffff9401 on Windows can be frustrating, but don't worry, we're here to help you resolve it! This error often occurs due to issues with the Windows Update service, caused by corrupted system files, incorrect system settings, or third-party software interference. Let's identify the root cause and apply the fixes to get your Windows Update service up and running smoothly.

Common Causes

  • Corrupted System Files: Corrupted or missing system files can cause the Windows Update service to malfunction, resulting in the 0xffff9401 error code. This can be due to a virus or malware infection, improper system shutdown, or software conflicts.
  • Incorrect System Settings: Incorrectly configured system settings, such as incorrect date and time, can also contribute to the occurrence of this error. It's essential to ensure that system settings are properly configured to prevent any potential conflicts with the Windows Update service.
  • Third-Party Software Interference: Third-party software, such as antivirus programs or firewalls, can sometimes interfere with the Windows Update service, causing the 0xffff9401 error code to appear. It's crucial to check for any potential software conflicts and resolve them accordingly.
  • Low Disk Space: Low disk space can also be a contributing factor to this error. Ensure that your system has sufficient free disk space to accommodate updates.

Step-by-Step Fixes

Method 1: Run the Windows Update Troubleshooter Show Steps ↓

Step 1: Open the Windows Update Troubleshooter.

  1. Go to Settings > Update & Security > Troubleshoot.
  2. Click on Additional troubleshooters.
  3. Find and click on Windows Update under Get up and running.
  4. Click on Run the troubleshooter and follow the prompts.
Method 2: Run the System File Checker Show Steps ↓

Step 1: Open the Command Prompt as an administrator.

  1. Right-click on the Start menu and select Command Prompt (Admin).

  1. Type sfc /scannow and press Enter to run the System File Checker.
  2. Wait for the scan to complete.
  3. Restart your computer and check for updates again.
Method 3: Check and Correct System Settings Show Steps ↓

Step 1: Ensure your system's date and time are correctly set.

  1. Right-click on the date and time in the system tray and select Adjust date/time.

  1. Make sure Set time automatically is enabled and the time zone is correctly set.
  2. Click on Sync now to synchronize your system's clock with online time servers.
Method 4: Disable Conflicting Software Show Steps ↓

Step 1: Identify any recently installed software that may be conflicting with the Windows Update service.

  1. Check for any antivirus programs or firewalls that may be interfering with Windows Update.
  2. Temporarily disable any identified software through Task Manager or System Configuration to test if it resolves the issue.

  1. If disabling the software resolves the issue, consider uninstalling it or configuring it to exempt the Windows Update service.
Method 5: Reset Windows Update Components Show Steps ↓

Step 1: Stop the Windows Update services.

  1. Open the Command Prompt as an administrator.
  2. Type net stop wuauserv and press Enter.
  3. Type net stop cryptSvc and press Enter.
  4. Type net stop bits and press Enter.

Step 2: Rename the Windows Update folders.

  1. Type ren C:\Windows\SoftwareDistribution SoftwareDistribution.old and press Enter.
  2. Type ren C:\Windows\System32\catroot2 catroot2.old and press Enter.

Step 3: Start the Windows Update services again.

  1. Type net start wuauserv and press Enter.
  2. Type net start cryptSvc and press Enter.
  3. Type net start bits and press Enter.

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