I’ve been having trouble for months with .NET 4.7.x updates on my Windows 7 main machine. I managed to get 4.7 to install last year, but 4.7.1 and 4.7.2 absolutely refused to install, throwing “error 643” which is about as non-specific as you can get.
Story goes that in order to fix this problem, you uninstall .NET and reinstall it. So I uninstalled .NET 4.7. Bad move, because that dumped me back to .NET 3.5 and a whole bunchatonastuff relies on .NET 4.x anymore, so when I rebooted a whole bunchatonastuff failed to start. And at that point, I was screwed, because even .NET 4.0 wouldn’t install.
Digging around on the net, I finally found the answer that worked:
Looks like the easiest fix to try is to rename C:\ProgramData\Microsoft\Crypto\RSA\S-1-5-18 to C:\ProgramData\Microsoft\Crypto\RSA\S-1-5-18_old and re-install. If that doesn’t work that link has other possible fixes.
Sure enough, that fixed it. So I’m making a note for myself, for when .NET 4.7.3 will probably refuse to install.
Edit to add: Why this was abysmally bad was that it actually had me considering an upgrade to Windows 10.
Edit 15 Aug 2018 to add: Why does Microsoft make it so FUCKING HARD TO FIND OUT WHAT VERSION OF THE .NET FRAMEWORK YOU HAVE INSTALLED????? This should be exposed somewhere sensible, like, shit, I dunno, the Control Panel/System and Security/System page in Windows 7? Jesus wept.