can not start phpmyadmin after upgrade to 2.10.3

[vuthecuong]

Today when after upgrade phpmyadmin through portupgrade from 2.10.2 to 
2.10.3
when I browse to phpmyadmin page, it said:


  phpMyAdmin - Error

Cannot start session without errors, please check errors given in your 
PHP and/or webserver log file and configure your PHP installation properly.

What's is this error?
How can I solve it?
Tnx in advanced