Solution for blank upgrade.php after upgrading

For ALL of the people here struggeling with a blank/white upgrade.php page after upgrading their wordpress, i found a solution which saved me 2 times already. I’m not sure i had this problem because i’m running my live blog on a Windows IIS server, but my Linux/Apache server upgraded without any problems.

Check out the file :
wp-admin/includes/schema.php

Somewhere on the top of the file is the line which reads:
if ( $wpdb->has_cap( 'collation' ) ) {

just replace that line with:
if ($wpdb->supports_collation()){

and your wordpress will be able to operate normally, and without any further problems.
So i think this is a small bug in the wordpress core, where some installations (basicly their server) won’t support the has_cap function for some reason. Perhaps a WP developer knows more about this, but it saved me 2 times already now. So good LUCK!