Upon updating to version 2017.4.1, the installer started to spew errors while writing the Environments folder, saying it could not write the exr files. Retrying didn't work so I aborted the install.
Now the Painter install folder has an empty Environments folder that I cannot open or delete, it has stripped all permissions from my Windows users (including Admin apparently). I cannot add ownership back to my account through the standard file onwership flags in an admin elevated command prompt, nor User Permissions tool. Access Denied always. It is now an irremovable folder preventing installs with 0 listed owners.
