Warning: session_start() [function.session-start]

help me, I have error, in my wordpress, after uppload in my hosting

Warning: session_start() [function.session-start]: open(/tmp/sess_552cbbd5757b12d3e8adc55d5aa31529, O_RDWR) failed: No such file or directory (2) in /home/aku/public_html/wp-content/themes/fruitful/inc/func/comment-inline-error.php on line 10

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at /home/aku/public_html/wp-content/themes/fruitful/inc/func/comment-inline-error.php:10) in /home/aku/public_html/wp-content/themes/fruitful/inc/func/comment-inline-error.php on line 10

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/aku/public_html/wp-content/themes/fruitful/inc/func/comment-inline-error.php:10) in /home/aku/public_html/wp-content/themes/fruitful/inc/func/comment-inline-error.php on line 10

and i can’t update plugin/wordpress, it’s show message box

Warning: touch() [function.touch]: Unable to create file /tmp/maintenance.tmp because No such file or directory in /home/aku/public_html/wp-admin/includes/file.php on line 155

Warning: unlink(/tmp/maintenance.tmp) [function.unlink]: No such file or directory in /home/aku/public_html/wp-admin/includes/file.php on line 500
Download failed. Could not open handle for fopen() to /tmp/maintenance.tmp

thank you