Authentication error while restarting apache

I'm connecting to my cloud server (OVH) using SSH key and now I'm trying to restart apache and gets this error:

ubuntu@server-1:~$ service apache2 reload
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to reload 'apache2.service'.
Authenticating as: Ubuntu (ubuntu)
Password:
polkit-agent-helper-1: pam_authenticate failed: Authentication failure
==== AUTHENTICATION FAILED ===
Failed to reload apache2.service: Access denied
See system logs and 'systemctl status apache2.service' for details.

How to solve it?

4 Answers

You must run that command using sudo as follow:

sudo service apache2 reload

Update:
If you have sudo: unable to resolve host server-1 problem, so you need to fix your hostname through /etc/hostname and /etc/hosts and reboot your linux machine to take affect. then retry above command again.
More details about this problem: Error message when I run sudo: unable to resolve host (none)

One option is to disable policykit (if you know what you're doing) via

sudo apt-get remove libpolkit-agent-1-0

You can find syntax error by this command -

sudo apache2ctl configtest

Fix the error. And things will work.

I took the list through this command sudo apache2ctl configtest and disable all warnings (with a2dissite <virtual_host_name>). And sudo systemctl restart apache2 or sudo systemctl start apache2 and my apache server started working.