Error: Unable to start session. Please check that the web server has enough permission to write to these files/directories:
For example, on a Linux server if your Apache httpd user
is www-data, you can try to execute:chown -R www-data:www-data /var/www/web1531/html/robisped.de/piwik/tmp/sessions/chmod -R 0755 /var/www/web1531/html/robisped.de/piwik/tmp/sessions/
Debug: the original error was Session must be started before any output has been sent to the browser; output started in /var/www/web1531/html/robisped.de/piwik/libs/Event/Notification.php/66