"Permission Denied" trying to run Python on Windows 10

Question

Seems as though an update on Windows 10 overnight broke Python. Just trying to run python --version returned a "Permission Denied" error. None of the three updates; KB4507453, KB4506991, or KB4509096 look like they'd be the culprit but the timing of the issue is suspicious. Rather than messing with rolling back, I'm hoping there's a simpler fix that I'm missing.

The permissions on python are "-rwxr-xr-x" and I haven't changed anything besides letting the Windows update reboot machine after installing last night's patches.

According to the System Information, I'm running 10.0.18362

Should also note that this is happening whether I (try) to execute Python from git-bash using "run as administrator" or not, and if I try using PowerShell, it just opens the Windows store as if the app isn't installed so I'm thinking it can't see the contents of my /c/Users/david/AppData/Local/Microsoft/WindowsApps/ folder for some reason.

I've also tried to reinstall Python 3.7.4, but that didn't help either. Is there something else I should be looking at?

Answer 1

As far as I can tell, this was caused by a conflict with the version of Python 3.7 that was recently added into the Windows Store. It looks like this added two "stubs" called python.exe and python3.exe into the %USERPROFILE%AppDataLocalMicrosoftWindowsApps folder, and in my case, this was inserted before my existing Python executable's entry in the PATH.

Moving this entry below the correct Python folder (partially) corrected the issue.

The second part of correcting it is to type manage app execution aliases into the Windows search prompt and disable the store versions of Python altogether.

It's possible that you'll only need to do the second part, but on my system I made both changes and everything is back to normal now.