Error Code: 0x80070643 (Windows Defender can't install definition updates)

Question

i keep getting a message stating windows defender cant instal definition updates, what should i do? should I remove the program and reinstall it? Thanks

Answer 1

Windows Update error 80070643

Windows Update error 80070643 can happen for several reasons. The most common cause is a problem with the .NET Framework installed on the computer. 

The .NET framework is a part of Windows that's used to build, deploy, and run programs and applications. Unfortunately, it can be damaged by some programs, viruses, or hard disk problems.

To repair the .NET Framework automatically

1. Click on the below link

Repair .NET Framework

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Answer 2

I did a manual update and, since then, no more troubles anymore.

It works great

Answer 3

Windows Update error 80070643

Windows Update error 80070643 can happen for several reasons. The most common cause is a problem with the .NET Framework installed on the computer. 

The .NET framework is a part of Windows that's used to build, deploy, and run programs and applications. Unfortunately, it can be damaged by some programs, viruses, or hard disk problems.

To repair the .NET Framework automatically

1. Click on the below link

         

Repair .NET Framework

---

If this post helps to resolve your issue, please click the "Mark as Answer" If you find it helpful , Mark it as helpful by clicking on "Helpful" button at the top of this message. By marking a post as Answered, or Helpful you help others find the answer faster.

This "answer" does not apply to Surface 2 devices and I'm getting the error in one of them.

Answer 4

I have this issue too but when I click on the "Repair .NET Framework" link, I'm asked to save the file "windowsupdate.diagcab" but it doesn't do anything. I tried unzipping it but there is no exe in there.

Answer 5

Thanks! This worked perfectly for me. I was getting the 80070643 error message just like "driesbach2004," mine a Vista 64 bit machine. Downloaded the Repair tool from the link provided, ran the tool and without a restart Defender was able to install updated definitions file.