Unable to update Windows Defender definitions with error code 0x80070643

[totally_not_a_corgi]

Windows 10 1709 x64


I have tried to update Windows Defender antivirus definitions to 1.259.218.0 but the update doesn't work, either with error code 0x80070643 when trying to do this through Windows Update or -2147023293 through Windows Defender Security Center. I have literally tried everything possible in order to fix this problem including contacting Microsoft, and the Answer Tech could not help me either.


- Windows Update troubleshooter: ran 3 times, no issues except for "unable to find automatic proxy server settings"

- Ran sfc /scannow and dism /online /cleanup-image /checkhealth, no problems. Twice.

- Uninstalled Malwarebytes which I was using alongside Windows Defender.

- Remote tech left behind a Reset Windows Update Tool which I have tried (which does things like restart BITS, etc.) No luck.

- Using the manual update mpam-feX64.exe results in nothing, the definitions don't update

- Multiple restarts


This problem also showed up with the earlier definitions 1.259.209.0

edit: I tried these command line switches, signature update doesn't work. Also below is the MpCmdRun.log for anyone who's on the Windows Defender team who knows what's going on

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


C:\WINDOWS\system32>"%programfiles%\Windows Defender\MpCmdRun.exe" -SignatureUpdate
Signature update started . . .
ERROR: Signature Update failed with hr=80070643
CmdTool: Failed with hr = 0x80070643. Check C:\Users\[name redacted]\AppData\Local\Temp\MpCmdRun.log for more information


-------------------------------------------------------------------------------------
MpCmdRun: Command Line: "C:\Program Files\Windows Defender\MpCmdRun.exe" -SignatureUpdate
Start Time: ‎Tue ‎Dec ‎12 ‎2017 15:15:45

Start: MpSignatureUpdate()
Update started
Search Started (MU/WU update) (Path: https://fe2.update.microsoft.com/v6/)...
Search Completed
Download Started...
Download Completed
Download Completed
Installation Started...
Update failed with hr: 0x80070643
Installation Completed
Update failed with hr: 0x80070643
Search Started (Direct HTTP) (Path: https://go.microsoft.com/fwlink/?LinkID=851034&clcid=0x409&arch=x64&eng=0.0.0.0&asdelta=0.0.0.0&prod=77BDAF73-B396-481F-9042-AD358843EC24)...
Download Started...
Time Info - ‎Tue ‎Dec ‎12 ‎2017 15:16:04 Download Completed
Installation Started...
Time Info - ‎Tue ‎Dec ‎12 ‎2017 15:16:21 Update failed with hr: 0x80508007
Installation Completed
Search Started (Direct HTTP) (Path: https://go.microsoft.com/fwlink/?LinkID=851036&clcid=0x409&NRI=true&arch=x64&eng=2.1.14202.0&sig=118.2.0.0&prod=77BDAF73-B396-481F-9042-AD358843EC24)...
Installation Completed
Update completed with hr: 0x80070643
ERROR: Signature Update failed with hr=80070643
MpCmdRun: End Time: ‎Tue ‎Dec ‎12 ‎2017 15:16:22
-------------------------------------------------------------------------------------


I am aware that 0x80508007 is an "out of memory" error - which makes absolutely NO logical sense as I have 16 GB of RAM installed on this computer and my memory usage is only 25-26% of that currently.

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