Fatal error: Call to undefined function wp_get_current_user() on WordPress 3.0.x
I’ve had this error for a few days and have been unable to access my dashboard:
Call to undefined function wp_get_current_user() in /html/wp-includes/capabilities.php line 1059.
In case you run into this problem since upgrading to WP 3 try adding this code after < ?php or on line 2 of capabilities.php:
It worked for me and has worked for errors appearing on other lines.
*** UPDATE: this will stop working after you do a WordPress update, so you might want to bookmark this page so you can keep reapplying the patch until they get it sorted.