No such interface 'org.freedesktop.DBus.Properties' on object at path /org/freedesktop/NetworkManager/ActiveConnection/

Question

I start my qt application in the user's .profile file (not root) to make the app start on boot. Sometimes when my application start, it reports an warning as below:

"No such interface 'org.freedesktop.DBus.Properties' on object at path /org/freedesktop/NetworkManager/ActiveConnection/1"

I searched on google but did not find a explanation.

It seems my app is still working fine, but I want to locate the problem.

The application is running on ubuntu and using Qt5.

Thanks in advance.

Edit
I tried to debug dbus based on Eligijus Pupeikis's help with running:

gdbus introspect --system \
            --dest org.freedesktop.NetworkManager \
            --object-path /org/freedesktop/NetworkManager/ActiveConnection

it returns:

node /org/freedesktop/NetworkManager/ActiveConnection {
  node 0 {
  };
};

So, this means there is no such object just as the error message said, right?
And also, this gns3 team member says this problem is about Qt and Ubuntu.

Does this mean I don't need to solve it? I not familiar with the relationship between dbus and qt.

Answer 1

Most likely there is no such object "/org/freedesktop/NetworkManager/ActiveConnection/1" and because of that it can't find 'org.freedesktop.DBus.Properties' interface.

From documentation org.freedesktop.NetworkManager.Connection.Active :

Objects that implement the Connection.Active interface represent an attempt to connect to a network using the details provided by a Connection object. The Connection.Active object tracks the life-cycle of the connection attempt and if successful indicates whether the connected network is the "default" or preferred network for access. NetworkManager has the concept of connections, which can be thought of as settings, a profile or a configuration that can be applied on a networking device. Such settings-connections are exposed as D-Bus object and the active-connection expresses this relationship between device and settings-connection. At any time a settings-connection can only be activated on one device and vice versa. However, during activation and deactivation multiple active-connections can reference the same device or settings-connection as they are waiting to be activated or to be deactivated.

You can't know that that ActiveConnection object with specifically index 1 exists so you need to check by reading ActiveConnections property from /org/freedesktop/NetworkManager object's org.freedesktop.NetworkManager interface.

To have better visualize and understand how it looks I suggest D-Bus debugger. If you are using Gnome check out D-Feet.