Error 0x80070643 while Installing Definitions Update for Windows Defender in Windows 10

One of the pretty common errors for Windows 10 users while Windows Defender is failing to install updates is an error message Definition Update for Windows Defender — KB********** — Error 0x80070643. Most likely, other updates for Windows 10 can be installed without problems in such cases.

In this article we will share solutions on how to fix error 0x80070643 while updating Windows Defender and install the necessary definition update for this Windows 10 built-in antivirus tool.

error 0x80070643 windows defender update

Installing Latest Definitions for Windows Defender Manually from Microsoft Website

Most likely, this method is a most effective to fix error 0x80070643. All you need to do is to download and install definitions for Windows Defender manually.

To do this, follow the next steps:

  1. Go to page and move to Manually download and install the definitions area;
  2. At Antimalware solution area near Windows Defender Antivirus for Windows 10 and Windows 8.1 choose the needed definition version to download (depends on your OS): 32-bit, 64-bit or ARM;
    0x80070643 definitions windows defender
  3. After you’ve downloaded the file – simply launch it to install the latest definitions manually. After the installation finishes (it can happen invisible for the user), go to Windows Defender Security Center —> Virus & Threat Protection —> Protection updates;
    0x80070643 windows defender update
  4. As a result, all of the latest definition updates for Windows Defender will be installed.
    0x80070643 windows defender definitions update

Additional Methods on How to Fix Error 0x80070643 while Installing Definitions Update for Windows Defender

There are a few more solutions to fix the issue, don’t forget to try them to:

  1. Try to perform a clean boot for Windows 10 and check if the problem with Windows Defender still persists;
  2. Sometimes other antivirus that have been installed on your machine earlier (like Norton or McAfee) can also cause error 0x80070643. Try to completely remove it from your system using its cleanup utility (or you can just temporary disable it), reboot the system and check if now you are able to install update for Windows Defender. If everything seems to be OK, you can now turn on (or re-install) your third-party antivirus again while Windows Defender is still turned on.
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We hope that one of the methods will be useful for you and help to fix error 0x80070643 while updating Windows Defender on Windows 10.

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