Cannot write to file AppSDKWrapper.dll

Server Version#: N/A
Player Version#: 1.91.0.129

I’ve been trying to reinstall Plex for Windows after a past problem, but now when I’m trying to reinstall I get the following error:

Error opening file for writing:
C:\Program Files\Plex\Plex\AppSDKWrapper.dll

Running the installer in Administrator mode doesn’t change anything, and as far as I can tell there’s no other running instances of Plex, given I uninstalled it.

Nevermind, it seems that even after closing the application and uninstalling it via Windows’ “Apps and Features”, there was still an instance running in the background that I had to dig around in the “Background Processes” of Task Manager for. Personally, I think when you close a program, it should actually close.