A DESCRIPTION OF THE PROBLEM :
Every time when I try to install Oracle 12c I got this error
[INS-30131] Initial setup required for the execution of installer validations failed.
Cause - Failed to access the temporary location.
Action - Ensure that the current user has required permissions to access the temporary location.

I tried everything that you suggested but nothing worked for me.
I found that bug is connected with computer NetBIOS name.


CUSTOMER SUBMITTED WORKAROUND :
I have shortened the NetBIOS name to 14 characters and after that everything worked well.

FREQUENCY : always