After updating a 3.4.2 network install to 3.5, I receive
Fatal error: Call to undefined function nocache_headers() in /wp-admin/admin.php on line 32
This happens in Chrome, and in Firefox (when I am not logged into admin).
I have downloaded a 3.5 zip, and uploaded and overwritten /wp-admin, but the issue remains.
I have also renamed plugins to plugins2, but the issue remains.