Windows Defender Error 0x80070643 Updating Definitions

When you attempt to update Windows Defender via Windows Update, error 0x80070643 may appear and the definition updates fail to install. Here is the full error message:

There were problems installing some updates, but we’ll try again later. If you keep seeing this and want to search the web or contact support for information, this may help:

Definition Update for Windows Defender – KB2267602 (Definition #.###.####.#) – Error 0x80070643

windows defender error 0x80070643
Windows Defender update error 0x80070643

What causes Error 0x80070643 in Windows Defender?

Error code 0x80070643 means “Fatal error during installation”. Like many error codes in Windows, this code isn’t helpful or descriptive at all. However, it may be caused by a server-side problem which means you don’t need to fix your Windows Update components or reset the SoftwareDistribution\Downloads folder. Here is a response for this issue, posted by Jason Yim, Windows Defender Team at Microsoft:

I just wanted to start a thread to have a chance to address everyone and inform you that the Windows Defender team is aware of the situation and working as quickly as possible to resolve the issue. We thank you for your patience and we should have a fix rolled out soon.

Meanwhile, for those running into the definition update error 0x80070643 (or protection definition error: -2147023293) we recommend you to manually get your machines back to a protected state by following the instructions outlined here

Please note the manual adl package is designed to update silently. To verify the manual update worked correctly please check with the Windows Defender (or SCEP) Client UI to see if it reports the latest threat definition version. The latest definition version can also be found in the link above.

All you need to do is try updating Windows Defender signatures after sometime, or use other methods listed below to update Windows Defender.

Workarounds for Windows Defender Error 0x80070643

Option 1. Update Windows Defender manually

Visit Definition updates page at Microsoft, download Windows Defender Antivirus Update package (mpam-fe.exe) for your Windows version and bitness and run it. It silently updates the Windows Defender signatures.



defender update mpam-fe.exe

Option 2: Use Windows Defender Command-Line Tool to Update the Signatures

Alternately, you can use the Windows Defender command-line tool MpCmdrun.exe to update the signatures. Open an Admin Command Prompt window and type these two commands exactly:

"%ProgramFiles%\Windows Defender\MPCMDRUN.exe" -RemoveDefinitions -All
"%ProgramFiles%\Windows Defender\MPCMDRUN.exe" -SignatureUpdate

The first command removes any installed signature and engine files, and this option is used when you have difficulties trying to update signatures. The 2nd command checks for the latest updates and installs it. In case the 2nd command fails with an error, use the alternate command to update the definitions directly from the Microsoft Malware Protection Center (MMPC) servers:

"%ProgramFiles%\Windows Defender\MPCMDRUN.exe" -SignatureUpdate -MMPC

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About the author

Ramesh Srinivasan founded Winhelponline.com back in 2005. He is passionate about Microsoft technologies and he has been a Microsoft Most Valuable Professional (MVP) for 10 consecutive years from 2003 to 2012.

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