openvpn gnome applet: Could not find source connection

[SVDEg]

lsb_release -rd
Description: Ubuntu 18.04.2 LTS
Release: 18.04

Packages:
network-manager-openvpn (1.8.2-1).
network-manager-openvpn-gnome (1.8.2-1).

All operation system updates by current date was installed.

I use a vpn applet to connect to my vpn server. I import the configuration from my ovpn-file.
Everything was fine. After system updates installation vpn won't works with the gnome vpn applet:

/var/log/syslog:

Jul 13 19:53:22 alex-pc NetworkManager[2185]: <info> [1563036802.6358] audit: op="connection-activate" uuid="0c66b073-67d4-425c-b4cf-1910460e073a" name="x1" pid=12760 uid=1000 result="fail" reason="Could not find source connection."

I found that the bug is very old(!):
https://bugzilla.gnome.org/show_bug.cgi?id=704595

I tried to import the openvpn configuration manually into the openvpn applet with the same result.
But if I use my openvpn from cli - everything is fine.

Help me please!

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Loris Albanese (lorisalbanese)]

Please, give a workaround or solve this bug. Actually it's not possible to activare a vpn (eg. l2tp) without a gui ... and my raspberry does not have a gui! thank you.