The other day I was getting this error on a script I was running when I moved my website to another web hosting company. I couldnt figure out why it was causing this error to appear.

Finally, to fix this i had to make changes in the php.ini file. These are the steps I took to get rid of this annoying error.

[BEWARE: back up your original php.ini file before you begin to do anything like this]

[ If you dont have shell access by your web hosting company, you're out of luck - you cant go further. Unless you can persued your web hosting company to make changes in their server configuration]

step:

• open your php.ini file. I was using Redhat so i executed this command to edit the file with linux nano editor: nano /etc/php.ini

• find and change the following line 

from display_errors = On

TO

display_errors = Off 

• save file by hitting control  + x
  
• reboot apache with this command: /etc/init.d/httpd restart
• done

Hopefuly you wont be getting this Warning: session_start(): error when you go back to reload your page. if you do, you may have done somethig wrong, either try again, or go back to the original file you backed up.