(nm-connection-editor:4592): Gtk-CRITICAL **: gtk_file_chooser_select_filename: assertion 'filename != NULL' failed

[Mr. Code Depot]

You can observe such messages spilling in stdout when:
1. run cmd nm-connection-editor
2. select openvpn -> create
3. select a cert file either for [user certificate] or [CA certificate]
4. observe continuous messages in the console:
nm-connection-editor:4628): Gtk-CRITICAL **: gtk_file_chooser_select_filename: assertion 'filename != NULL' failed

(nm-connection-editor:4628): Gtk-CRITICAL **: gtk_file_chooser_select_filename: assertion 'filename != NULL' failed

** (nm-connection-editor:4628): WARNING **: Invalid setting VPN: remote

** (nm-connection-editor:4628): WARNING **: Invalid setting VPN: remote

** (nm-connection-editor:4628): WARNING **: Invalid setting VPN: remote

** (nm-connection-editor:4628): WARNING **: Invalid setting VPN: remote

** (nm-connection-editor:4628): WARNING **: Invalid setting VPN: remote

** (nm-connection-editor:4628): WARNING **: Invalid setting VPN: remote

My env:
Description: Ubuntu 14.04.3 LTS
Release: 14.04

network-manager-openvpn:
  Installed: 0.9.8.2-1ubuntu4
  Candidate: 0.9.8.2-1ubuntu4
  Version table:
 *** 0.9.8.2-1ubuntu4 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status
network-manager-openvpn-gnome:
  Installed: 0.9.8.2-1ubuntu4
  Candidate: 0.9.8.2-1ubuntu4
  Version table:
 *** 0.9.8.2-1ubuntu4 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/universe amd64 Packages
        100 /var/lib/dpkg/status
network-manager:
  Installed: 0.9.8.8-0ubuntu7.1
  Candidate: 0.9.8.8-0ubuntu7.1
  Version table:
 *** 0.9.8.8-0ubuntu7.1 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu/ trusty-security/main amd64 Packages
        100 /var/lib/dpkg/status
     0.9.8.8-0ubuntu7 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages