I keep seeing this message periodically when launching things from the command line. For example, I launched keepass2, and I get this message:
Gtk-Message: 20:24:04.576: Failed to load module "canberra-gtk-module"
Here’s the simple fix … install the libcanberra-gtk-module. Here’s the command-line:
sudo apt install libcanberra-gtk-module
That fixed my problem! Note: the only symptom was just the warning on the console. I didn’t notice any other issues caused by not having that module.