Multiple places online often suggest fixes for Windows Update error “0x80070643” by expanding the Windows Recovery Environment (“WinRE”) partition, citing a need for one at least 250MB free space.
I have an 8GB WinRE partition, so that was definitely not it.
Funnily enough, after several hours crawling through pages, I found this page, and “Fix #6” actually worked for me…
i.e. Run the .NET Framework Repair Tool…
As per usual, YMMV…
