Installation failed / Failed to install a dependency 
Quick background, an addon I had been using stopped working a few days ago. Apparently it got an update, but it failed to install. I tried several times and it always failed. I downloaded the file and tried to install from a zip file, and that failed. I tried to install or update other addons, and all of them failed. Finally this morning, I uninstalled everything, including Kodi profile stuff (the extra checkbox during uninstall) to make sure everything was gone. I then rebooted my PC (Win 10) and installed a clean version of Kodi.
The first thing I tried after that was finished was to setup a weather provider, Installation failed. Then I tried to install the YouTube addon, Installation failed. So I came here, read a few threads, didn’t see my specific problem, and in preparation for this thread, went about trying to get a debug file to link to. The first step in generating a debug file says to install Kodi Logfile Uploader, so I tried that, several times, and only get “Installation failed” for something called pyQRcode, followed by “Failed to install a dependency” for the Kodi Logfile Uploader. This is all currently on Kodi 17.5 Beta build, though I had the same problems on 16.1 prior to uninstalling all Kodi information.
Also, I have disabled firewall and anti-virus software, even though everything had been working with those on prior to all of this. Does anyone have any idea why nothing will install, while every other thing I try that requires an internet connection works without the slightest issue?