I installed newest versions of MySQL, IIS (on windows 10) and PHPMyAdmin.
But PHPMyAdmin 4.6.4 returns an error:
Failed to generate random CSR
royhutw is kind of right.
The default session.save_path is C:\Windows\Temp. If you're getting this error IIS probably doesn't have permissions to create a session file there.
Only thing you'll have to do is give "IUSR" modify permissions on this folder and reload your phpMyAdmin page.