Error 500 on accessing update.php
The errors output to Apache are often somewhat cryptic.

You probably want to check the Drupal Reports page, dblog, and the Apache logs.

This sounds like one of the new updates has a problem in the .install or cannot be loaded (permission problems, although that comes proper from Drupal, I never had that problem on an upgrade.)

To test whether the PHP code is invalid, you can run

 php &lt;filename&gt;


The update.php will generate some errors, but it should not tell you it cannot parse it. All the module .install should not generate any errors (a very few modules have code outside functions and those will generate errors, but again no syntax error.) Those syntax error are reported by Apache.