Windows Defender update fails, error code 0x80070643

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.

Fix: 0x80070643 Windows Defender update error

Windows Defender offers solid protection, but if you want to keep your PC protected, it’s important to update Windows Defender regularly. Unfortunately, update issues can occur, and speaking of issues, these are some of the common problems that users reported:

  • Windows Defender update failed – If Windows Defender update fails, the issue might be a third-party antivirus tool. If your previous antivirus isn’t completely removed, sometimes leftover files can interfere with Windows Defender and cause this issue to appear. To fix it, simply remove any leftover files and the issue should be fixed.
  • Windows Defender update stuck – Sometimes your Windows Defender can get stuck during the update process. If this happens, be sure to repair your system files using both SFC and DISM scans.
  • Windows Defender update connection failed – If you get this error message while trying to update Windows Defender, your third-party firewall might be an issue, so be sure to disable it or uninstall it.
  • Windows Defender update won’t install – If Windows Defender update won’t install, the issue might be a problematic application. However, you can fix the issue simply by performing a Clean boot.
  • Windows Defender not getting updated – Several users claim that this issue can be caused by Windows Update components, so try resetting them and check if that solves the problem.

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.

You can also remove your antivirus or any leftover files by using the uninstaller software. These applications are specially designed to remove the selected application along with all of its files and registry entries. As a result, the application will be completely removed from your PC.

There are many great uninstaller tools available on the market, but the best are IOBit Uninstaller and Revo Uninstaller so feel free to try any of these tools.

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. To perform an SFC scan, you need to do the following:

  1. Press Windows Key + X and choose Command Prompt (Admin) from the menu. You can also use PowerShell (Admin).
  2. Type the command sfc /scannow > hit ENTER > wait for the scan to complete.

If you can’t run SFC scan or if SFC didn’t solve the problem, you might have to use DISM scan instead. To do that, just follow these steps:

  1. Start Command Prompt as administrator.
  2. Now run DISM /Online /Cleanup-Image /RestoreHealth and press Enter to run it.
  3. DISM scan will now start. Keep in mind that this scan can take up to 20 minutes or more, so don’t interrupt it.

Once the DISM scan is finished, check if the problem is resolved. If the issue still persists, or if you weren’t able to run SFC scan before, try running the SFC scan again and check if that solves the problem.

Solution 3 – Perform a Clean boot

Third-party applications can sometimes interfere with Windows and cause Windows Defender update to fail and error 0x80070643 to appear. However, you might be able to fix the issue simply by performing a Clean boot. This is rather simple and you can do it by following these steps:

  1. Press Windows Key + R and enter msconfig. Press Enter or click OK.
  2. System Configuration window will now appear. Go to Services tab and check Hide all Microsoft services. Now click Disable all button.
  3. Now go to Startup tab and click Open Task Manager.
  4. List of startup applications will now appear. Select the first item on the list, right-click it and choose Disable from the menu. Now repeat this step for all startup applications.
  5. Once you disable all startup applications, close Task Manager and go back to System Configuration window. Click Apply and OK to save changes. Now restart your PC.

Once your PC restarts, check if the problem still appears. If not, go back and enable disabled apps and services one by one until you find the one that is causing the issue. Once you find it, delete it or disable it, and the problem will be permanently resolved.

If the issue still persists, we also recommend you to download this tool  (100% safe and tested by us) to scan and fix various PC problems, such as file loss, malware and hardware failure.

Solution 4 – Restart the Security Center Service

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

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.

Solution 6 – Disable .NET Framework

According to users, sometimes .NET Framework can cause problems with Windows Defender updates. However, you might be able to fix this problem simply by disabling .NET Framework. To do that, just follow these steps:

  1. Press Windows Key + S and enter features. Select Turn Windows features on or off.
  2. When Windows Features window opens, disable Windows Communication Foundation HTTP Activation and Windows Communication Foundation Non-HTTP Activation. Now click OK to save changes.

Now you just have to restart your PC and the issue should be resolved completely. Several users are suggesting to repair your .NET Framework installation as a potential solution, so you might want to try that as well.

Solution 7 – Install and then remove a third-party antivirus

This is a strange workaround, but several users reported that they fixed error code 0x80070643 simply by installing and then removing a third-party antivirus. Few users reported that they fixed the issue simply by installing a free third-party antivirus and after removing it, the problem was resolved.

This is a peculiar workaround, but it works according to users, so we advise you to try it out.

Solution 8 – Check for updates from Windows Defender

If you’re having problems with downloading updates, you might be able to fix the problem by trying to download updates directly from Windows Defender. To do that, just follow these steps:

  1. Press Windows Key + I to quickly open the Settings app. Go to Update & Security section.
  2. In the left pane, select Windows Defender and then click Open Windows Defender Security Center button.
  3. Go to Virus & threat protection section.
  4. Now go to Protection updates.
  5. Now click Check for updates button.

Windows Defender will now download the available updates. Several users reported that this method worked for them, so feel free to try it out.

Solution 9 – Reset Windows Update components

Sometimes there might be a bug with Windows Update components, and that can cause 0x80070643 error to appear. However, you might be able to fix the problem simply by running several commands in Command Prompt. To do that, just follow these steps:

  1. Start Command Prompt as administrator.
  2. Now enter the following commands:
  • net stop wuauserv
  • net stop cryptSvc
  • net stop bits
  • net stop msiserver
  • ren C:WindowsSoftwareDistribution SoftwareDistribution.old ren C:WindowsSystem32catroot2 Catroot2.old
  • net start wuauserv
  • net start cryptSvc
  • net start bits
  • net start msiserver

By running these commands, you’ll stop all services associated with Windows Update, rename the affected directories and then restart the services. This is a simple solution, so feel free to try it out.

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

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