Changing session_save_path does not work

[sandermb]

When changing the session save path to a directory within my project with the PHP function session_save_path() it does not work.
It does change the directory and creates the session file within the given directory, but the session file remains empty.
When I use the default session save path there is no problem.

[yadakhov]

The webserver can't simply write to any folders without first given permission.

To make a folder writable by the webserver have to run a chmod command

chmod o+w -R your_save_path_folder