FIX: Windows Defender update failed [Connection error]

by Madalina Dinita
Madalina Dinita
Madalina Dinita
Windows & Software Expert
Madalina has been a Windows fan ever since she got her hands on her first Windows XP computer. She is interested in all things technology, especially emerging technologies... read more
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  • The error code 0x80070643 appears mostly when updating the Windows Defender.
  • Make sure you uninstall previous antiviruses that might interfere with the update.
  • You can also perform SFC and DISM scans to allow the PC to get rid of the issue.
  • Another solution would be turning off the Defender and switching to a better security tool.
fix windows defender update failed

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Users are complaining that the Windows Defender update fails to install due to the 0x80070643 error code. Actually, this error has been randomly plaguing Windows Defender users for a while now.

Judging by the number of views from the first Microsoft forum thread regarding the error 0x80070643, it’s no exaggeration to state that tens of thousands of users have encountered this problem.

Windows Defender offers solid protection, but if you want to keep your Windows 10 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 / security intelligence update error – Several users claim that this issue can be caused by Windows Update components, so try resetting them and check if that solves the problem.

How do I fix Windows Defender update error 0x80070643?

1. Use antivirus removal tools

When you uninstall a third-party antivirus using the Uninstall option from Control Panel, some files might remain undetected, preventing you from running and updating Windows Defender.

Even if you already uninstalled your previous antivirus and you’ve been using Windows Defender for quite some time without any problems, you’re not safe.

The remnants of your previous antivirus may now be causing the 0x80070643 Windows Defender error, and since they are hard to manually remove, you need to deal with them some other way.

This is where uninstaller software comes in handy so you can remove your antivirus or any leftover files. It is specially designed to remove the selected application along with all of its files and registry entries, leaving a clean space.

Completely uninstall your old antivirus programs, restart your computer and Windows Defender should be able to install the latest updates.

2. Check your system files

  1. Press Windows Key + X and choose Command Prompt (Admin) from the menu.
  2. You can also use PowerShell (Admin).
    Windows Defender not getting updated
  3. Type the following command and hit Enter: sfc /scannow
    Windows Defender update connection failed

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:

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

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

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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 an SFC scan before, try running the SFC scan again and check if that solves the problem.

3. Perform a Clean boot

  1. Press the Windows Key + R and enter msconfig.
  2. Press Enter or click OK.
    Windows Defender update won't install
  3. The System Configuration window will now appear.
  4. Go to the Services tab and check Hide all Microsoft services.
  5. Now click Disable all button.
    Windows Defender update failed
  6. Go to the Startup tab and click Open Task Manager.
    Windows Defender update stuck
    • A list of startup applications will now appear.
  7. Select the first item on the list, right-click it and choose Disable from the menu.
  8. Now repeat this step for all startup applications.
    Windows Defender update connection failed
  9. Once you disable all startup applications, close Task Manager and go back to the System Configuration window.
  10. Click Apply and OK to save changes and restart your PC.
    Windows Defender update won't install
  11. 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.
  12. When you find it, delete or disable it, and the problem will be permanently resolved.

Third-party applications can sometimes interfere with Windows and cause Windows Defender update to fail and error 0x80070643 to appear. You might be able to fix it by performing a Clean boot.

4. Use a third-party antivirus software

If you want to avoid all the problems related to Windows Defender, you can switch to a better security tool, such as third-party antivirus software.

Not only will this software do a better job at protecting your data from being stolen, or stop any virus from infecting your device. It should also have no errors or glitches.

You will also benefit from other useful features meant to protect your PC and allow you to browse the internet carelessly and without worry.

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5. Restart the Security Center Service

  1. Press Windows key + R and launch run.
  2. Type services.msc and hit Enter.
    Windows Defender not getting updated
  3. In the Services tab, search for Security Center.
  4. Right-click on Security Center, then click on Restart.
    Windows Defender update connection failed

6. Perform a final manual update

  1. Go to Microsoft’s Malware Protection Center portal.
  2. Follow the instructions to download and install both the Antimalware and antispyware updates and Network Inspection System updates available for your system.
Note icon
The manual ADL packageu00a0update installs 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.

7. Disable .NET Framework

  1. Press the Windows Key + S and enter features.
  2. Select Turn Windows features on or off.
    Windows Defender update stuck
  3. When the Windows Features window opens, disable Windows Communication Foundation HTTP Activation and Windows Communication Foundation Non-HTTP Activation.
  4. Now click OK to save the changes.
  5. Restart your PC and check if the problem is solved.

According to people, sometimes .NET Framework can cause problems with Windows Defender updates. You might be able to fix this problem simply by disabling it.

Several users are suggesting repairing your .NET Framework installation as a potential solution, so you might want to try that as well.

8. Check for updates from Windows Defender

  1. Press Windows Key + I to quickly open the Settings app.
  2. Go to the Update & Security section.
    Windows Defender update failed
  3. In the left pane, select Windows Defender and then click Open Windows Defender Security Center button.
    Windows Defender update connection failed
  4. Then, go to Virus & threat protection section.
    Windows Defender update stuck
  5. Now go to Protection updates.
    Windows Defender update won't install
  6. Click Check for updates button.
    Windows Defender not getting updated

Windows Defender will now download the available updates. Several users reported that this method fixes the kb2267602 error 0x80070643 for them, so feel free to try it out.

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.

9. Reset Windows Update components

  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

Sometimes there might be a bug with Windows Update components, and that can cause 0x80070643 Defender error to appear. You might be able to fix the problem by running several CMD commands.

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

We’ve written extensively about Defender update problems before. Bookmark this useful article dedicated to Windows Defender update issues in case you need it later.

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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Frequently Asked Questions

  • Security intelligence update is a constantly updated database of threats and malware used by Windows Defender to determine if certain files are malicious.

  • If you get the 0x80070643 error message, usually that means that the system settings were configured incorrectly, or you’ve been exposed to malware or viruses. Here is a plentiful list of antivirus software to protect yourself.

  • Use antivirus-specific removal tools and check your system files. If that doesn’t work, follow our step-by-step guide dedicated to fixing Windows Defender update issues.

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