Here’s how to fix Windows Defender error 0x8000404

By: Madeleine Dean
2 minute read

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Updating Windows Defender can sometimes be quite a tricky task. There are various errors that can block the update process, but fortunately most of them can be fixed using quick workarounds.

Error code 0x8000404 is one of the most frequent errors encountered by Windows Defender users, and appears when the definition updates can’t be installed.

I have tried three times to install the Virus & Spyware updates, the defination updates couldn’t be installed, the error code 0x8000404 – what do I have to do?

There are several possible causes for this error: another security program creates conflicts and blocks Windows Defender updates, some system files are corrupt or missing, the Internet connection in unstable, and more.

Fix Windows Defender error 0x8000404

We are going to list several possible solutions to fix this error code. After you follow the troubleshooting steps of each workaround, try to update Windows Defender. If it doesn’t work, go to the next solution.

1. Temporarily disable any other security software you are running, and try to update Windows Defender.

2. Run a SFC scan:

  1. Go to Start > type cmd in the Search box > right-click Command Prompt > click Run as administrator

  2. For various PC problems, we recommend this tool.

    This software will repair common computer errors, protect you from file loss, malware, hardware failure and optimize your PC for maximum performance. Fix PC issues now in 3 easy steps:

    1. Download this PC Repair Tool rated "Excellent" on TrustPilot.com.
    2. Click “Start Scan” to find Windows issues that could be causing PC problems.
    3. Click “Repair All” to fix all issues with Patended Technologies (requires upgrade).

  3. At the command prompt, type the sfc /scannow command > press Enter
  4. Try to update Windows Defender again.

3. Perform a Clean Boot

  1. Type System Configuration in the search menu > open the first result
  2. Go to the Services tab > select the Hide all Microsoft services check box > click Disable all
  3. Go to the Startup tab > click Open Task Manager
  4. In Task Manager > select each startup item > click Disable
  5. Close the Task Manager
  6. Go back to the Startup tab > click OK > restart the computer.

4. Delete any suspicious programs

Go to Control Panel > open Uninstall a program > delete any suspicious program.

If you’ve come across other workarounds to fix Windows Defender error 0x8000404, list the troubleshooting steps in the comment section below.

RELATED STORIES YOU NEED TO CHECK OUT:

For various PC problems, we recommend this tool.

This software will repair common computer errors, protect you from file loss, malware, hardware failure and optimize your PC for maximum performance. Fix PC issues now in 3 easy steps:

  1. Download this PC Repair Tool rated "Excellent" on TrustPilot.com.
  2. Click “Start Scan” to find Windows issues that could be causing PC problems.
  3. Click “Repair All” to fix all issues with Patended Technologies (requires upgrade).

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