Bdtyktl

One solution is to start:

nm-connection-editor

in the terminal. Terminal messages will tell you which entries of the connection are considered as invalid.

Source: https://bugs.launchpad.net/ubuntu/+source/network-manager-openvpn/+bug/990765/comments/27

Read this thread.
The problem originates from the security policy implemented in Ubuntu.
You will be required to change this as described in the displayed thread.

The file is /usr/share/polkit-1/actions/org.freedesktop.NetworkManager.policy, edit it with:

sudo -H gedit /usr/share/polkit-1/actions/org.freedesktop.NetworkManager.policy

You need to change the action:

<action id="org.freedesktop.NetworkManager.settings.modify.own">

.

.

.

<allow_inactive>no</allow_inactive>

to read

<allow_inactive>auth_admin</allow_inactive>

or

<allow_inactive>yes</allow_inactive>

logout to activate.

As Enrique said in this post: https://askubuntu.com/a/143491/98277

Make sure these fields are populated:

    User Certificate

    CA certificate

    Private Key



Your Save button will work then.

I ran into this issue with LUbuntu 18.04. To try to add my VPN from a ovpn file, I ran:

sudo nm-connection-editor

But when I tried to add from the existing ovpn file, the save icon was grayed out. I noticed on the command line I saw this error:

 Could not load editor VPN plugin for “org.freedesktop.NetworkManager.openvpn” (missing plugin file "/usr/lib/x86_64-linux-gnu/NetworkManager/libnm-vpn-plugin-openvpn-editor.so"

I was able to solve the problem by installing an additional package that was missing:

sudo apt-get install network-manager-openvpn-gnome

Are you sure you need exactly OpenVPN? In case you need to have vpn connection only with login and password (no certificate needed) try using PPTP.

sudo apt-get install network-manager-pptp

sudo network-manager restart

Click to NetworkManager -> Configure VPN -> +Add -> Point-To-Point Tunneling Protocol (PPTP) in VPN section.

I had the same issue on Ubuntu Mate 16.10

Turns out it wouldn't work while connected from a Windows PC through xRDP. I tried it on the box locally and I was able to save the OpenVPN configuration and managed to connect.

TLDR: Disconnect from xRDP and try to save it locally

I had a similar problem with creating an openvpn connection in the gnome network manager.

I discovered that it expects you to enter a password in the "Private Key Password:" field. If your openvpn server doesn't require a password, then you need to click on the tiny little icon on the right side of the "Private Key Password:" field and select "The password is not required". You will then be able to click the "Save" button.

I know this is super old, but I recently ran into the same issue. And there is no actual answer here, just a bunch of things to try.

I have found the answer:

The Apply button is disabled if the current settings don't pass validation.

If you run nm-connection-editor by itself, then select your VPN connection, you will see an error that explains what can't be saved.

Correct those issues and the Apply button will become enabled.

In my case, I found that I didn't have a user name in the Identity > Authentication > User name field. Once I added my user name, the Apply button instantly enabled.

Hope this helps.