There are different reasons for PHP session not working.
If the session is using file.(By Default it is File Only)
1) If you are using Linux OS, Make sure the the session file is writable.
2) Make sure the session path is SET in php.ini.
Example:
session.save_path = "D:/wamp64/tmp"If the session is using database.
1) Check the db settings properly.
2) Make sure no other errors related to headers.
