WARN Piwik\Session[2019-12-11 21:38:48] [7cac0] Unable to start session: session has already been started by session.auto-start or session_start()
Piwik › Error
Piwik # Web Analytics

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 /home/var/www/html/com/net-profil/subdomains/stats/tmp/sessions/
chmod -R 0755 /home/var/www/html/com/net-profil/subdomains/stats/tmp/sessions/

If you still experience issues after trying these changes, we recommend that you enable database session storage.

Debug: the original error was 
session has already been started by session.auto-start or session_start()

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