Ubuntu 18.04: No polkit authentication agent found

Question

I get the error message above when I try to write to a file I don't have permission to in Visual Studio Code. I choose "Retry as sudo": Click sudo and get the error: Error message

This only happens when I connect to the machine from my PC using ssh and X11-forwarding. Not when I run from gnome directly on Ubuntu machine.

Help appreciated.

Output from "systemctl status polkit.service"  

Sep 02 20:03:19 rolf-PE-860 systemd[1]: Starting Authorization Manager...
Sep 02 20:03:19 rolf-PE-860 systemd[1]: Started Authorization Manager.
Sep 02 20:03:19 rolf-PE-860 polkitd[4155]: started daemon version 0.105 using authority implementation `local' version `0.105'
Sep 02 20:03:19 rolf-PE-860 polkitd(authority=local)[4155]: Registered Authentication Agent for unix-session:14 (system bus name :1.80 [/usr/bin/gnome-shell], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Sep 02 20:03:19 rolf-PE-860 polkitd(authority=local)[4155]: Registered Authentication Agent for unix-session:c2 (system bus name :1.40 [/usr/bin/gnome-shell], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Sep 02 20:03:45 rolf-PE-860 polkitd(authority=local)[4155]: Registered Authentication Agent for unix-process:4160:201286 (system bus name :1.124 [/usr/bin/pkttyagent --notify-fd 5 --fallback], object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8)
Sep 02 20:03:51 rolf-PE-860 polkitd(authority=local)[4155]: Operator of unix-process:4160:201286 successfully authenticated as unix-user:rolf to gain ONE-SHOT authorization for action org.freedesktop.systemd1.manage-units for system-bus-name::1.125 [systemctl start polkit.service] (owned by unix-user:rolf)
Sep 02 20:03:51 rolf-PE-860 polkitd(authority=local)[4155]: Unregistered Authentication Agent for unix-process:4160:201286 (system bus name :1.124, object path /org/freedesktop/PolicyKit1/AuthenticationAgent, locale en_US.UTF-8) (disconnected from bus)

Solution

I met up with the same problem recently. I'm a newbie, so I don't know whether this can solve your problem, but here is my solution.

1. find out which desktop environment I'm using

   ps -A | egrep -i "gnome|kde|mate|cinnamon|lx|xfce|jwm"
   

2. search for the corresponding policykit package and install it.

   sudo apt search policykit
   sudo apt install policykit-1-gnome
   

   my desktop environment is GNOME

3. (I don't know whether this step is necessary)

   exec /usr/lib/policykit-1-gnome/polkit-gnome-authentication-agent-1
   

and then my problem had gone.

Comments

[damadam]

Can you add the source link of this solution (because it's sure that it's ot from you)?

[John Smith]

Doesn't fix the problem (SE is batting .1000 on non-working solutions for Ubuntu, it seems.) I'm having this issue and the right policykit is already installed. The last step just returns an error.

[ATorras]

3rd step is necessary if no Gnome shell interaction is done (i.e. ssh)

[balu]

This did the trick for me! I'm using a custom desktop environment, so I had to install policykit-1-gnome manually. Once I started it (step 3), everything worked as expected!