Hi,

When clicking the "Register" button, there is a php_warning:
array_key_exists() [<a href='function.array-key-exists'>function.array-key-exists</a>]: The second argument should be either an array or an object in /data1/www/apache2php52/ezporacle/.run/kernel/classes/ezpersistentobject.php on line 123

Steps to reproduce

• Access the plain_site
• Click on register button
• register the new user
• when commiting the new user information the error is raised