Microsoft Security Essentials Install Error 0x80070643
This is Microsoft support, Morlad speaking, how can I help you?
While trying to update Microsoft Security Essentials to the newly released version 2, the installation failed with the remarkably descriptive error
0x80070643. Looking for a solution on the web was no help either.
So I tried to solve the problem by uninstalling the old version. Installing all critical and optional updates via Windows Update. Rebooting multiple times while doing so. Deactivating Microsoft Defender’s real-time protection. Sacrificing two goats and finally handing over my soul to the devil. But nothing worked.
At the end I got it to work. However, I changed two things at once before trying to install MSE2 again, so I’m not sure which one of those changes actually fixed the problem. But here you go:
- STOP the “Windows Defender”-service (I don’t think that solved the problem)
- START the “Windows Firewall”-service (But this one did, I guess)
As I don’t use Microsoft Firewall (or any other firewall software), I didn’t just deactivate the firewall but stopped the service altogether. That seems to have bothered the installer.
Now MSE2 is installed and working properly and with that: the option to opt-out of SpyNet.