Fix: Windows Defender update fails, error code 0x80070643

By: Madeleine Dean
3 minute read

Microsoft pushed out an update for Windows Defender on the same day it released the Anniversary Update, but more than a week after the event, some users are still trying to install the KB2267602 update. They are complaining the Windows Defender update fails to install due to the 0x80070643 error code.

Actually, this error has been randomly plaguing Windows Defender users for more than a year now, but Microsoft hasn’t been able to offer a solid explanation as to why this error appears, let alone a fix. Judging by the number of views from the first Microsoft forum thread regarding error 0x80070643, it’s no exaggeration to state that tens of thousands of users have encountered this annoying error code.

Windows Defender update install fails due to error 0x80070643

Windows Defender update (KB2267602) fails-error code 0x80070643. What is up? My Dell laptop has been doing nicely since I added W10. Now, the above listed error has occurred The Dell came with W8.1 OS. I updated a month or so ago. I have checked update history and it says 0 updates have been installed, but I got one last night. It said it would download and restart several times.

Fix: 0x80070643 Windows Defender update error

Solution 1 – use antivirus specific removal tools

When you uninstall a third-party antivirus solution using the Uninstall option from the Control Panel, it’s possible that some files remain undetected and this prevents you from properly running Windows Defender or installing updates. Check out this list of antivirus removal tools, and run the tool available for the antivirus you used before installing Windows Defender.

Even if you already uninstalled your previous antivirus and you’ve been using Windows Defender for quite some time without any problems, the remnants of your previous antivirus may now be causing the 0x80070643 error. Completely uninstall your old antivirus programs, restart your computer and Windows Defender should be able to install the latest updates.

Solution 2- check your system files

The System File Checker tool repairs corruption in system files. Use this tool to verify whether Windows Defender is corrupted or not, which could explain why you can’t install the updates.

  1. Type cmd in the search box > right-click Command Prompt > Run as administrator.
  2. Type the command sfc /scannow > hit ENTER > wait for the scan to complete.

Solution 3 – clean boot your computer

  1. Type System Configuration in the search box > hit Enter
  2. On the Services tab >  select the Hide all Microsoft services check box > click Disable all.

hide all microsoft services windows 10

3. On the Startup tab > click on Open Task Manager.

4. On the Startup tab in Task Manager > select all items > click Disable.

disable start up items windows 10

5. Close the Task Manager.

6. On the Startup tab of the System Configuration dialog box >click OKrestart your computer.

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Solution 4 – Restart the Security Center Service

  1. Press Windows key + R > launch Run.
  2. Type services.msc > hit enter.
  3. In Services, search for Security Center.
  4. Right click on Security Center > click on Restart.

security center windows 10

We hope these fixes work for you. If you’ve found other workarounds, tell us more about your experience in the comment section below.

Solution 5- Perform a final manual update

1. Go to Microsoft’s Malware Protection Center portal

2. Follow the instructions to the letter and download and install both the “Antimalware and antispyware updates” and “Network Inspection System updates” available for your system.

The manual ADL package update install silently. To make sure that the manual update worked correctly, check with the Windows Defender Client UI to see if it reports the latest threat definition version. The latest definition version is also available in the link above.

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