Cfrgtkky

The warning is

** (/usr/lib/firefox/firefox:1671): WARNING **: 22:14:54.614: Unable to connect to dbus: Could not connect: Permission denied

I tried using strace but can't find any related file errors there. I guess it could be AppArmor. Any suggestion on how to find the cause?

I started to search because no matter Visual bell setting is set to (gsettings set org.gnome.desktop.wm.preferences visual-bell false) Firefox flashes whole window to inverse colors when search on page did not return any results and it's annoying. This was fixed by changing KDE settings.

• libappmenu-gtk*-parser0 0.7.1-1


• Firefox 65.0 (both installed through apt and downloaded)


• D-Bus 1.12.12-1ubuntu1


• Ubuntu 19.04

I had ~/.dbus/ owned by root somehow, but tried changing owner to my user recursively and deleting the folder. Both times nothing changed even after a complete reboot.

I would've reported it as bug but want to make sure it really is one.

Update

It's not Firefox, it's appmenu-gtk*:

$ grep "Unable to connect to dbus" -rF /usr

Binary file /usr/lib/x86_64-linux-gnu/gtk-3.0/modules/libappmenu-gtk-module.so matches

Binary file /usr/lib/x86_64-linux-gnu/gtk-2.0/modules/libappmenu-gtk-module.so matches

And after removing the warning changed to

Gtk-Message: 16:30:03.964: Failed to load module "appmenu-gtk-module".

From reading the output of strace linked in the comments , here's what I found:

[pid  4245] sendto(35, "AUTHrn", 6, MSG_NOSIGNAL, NULL, 0) = 6

[pid  4245] recvfrom(35, "REJECTED EXTERNALrn", 4096, 0, NULL, NULL) = 19

[pid  4245] sendto(35, "AUTH EXTERNAL 31303031rn", 24, MSG_NOSIGNAL, NULL, 0) = 24

[pid  4245] recvfrom(35, "OK f9c00ca7570590f878c4db8c5c686"..., 4096, 0, NULL, NULL) = 37

What this means is that firefox ( client ) is connected to D-Bus (server) socket which is referenced by file descriptor number 35, which you can see earlier in the strace output:

[pid  4245] connect(35, {sa_family=AF_UNIX, sun_path="/run/user/1001/bus"}, 110) = 0

and initiates negotiation via standard commands described in D-Bus documentation. According to the documentation:

If an AUTH command has no arguments, it is a request to list available mechanisms. The server must respond with a REJECTED command listing the mechanisms it understands, or with an error.

REJECTED EXTERNAL response indicates response that the bus accepts EXTERNAL method of authentication. So the warning message likely came from the initial exchange. However, it later succeeds with the AUTH EXTERNAL method.

Thus, the conclusion I draw from this is that

1. this is not a firefox bug, though might be a false positive


2. the fact that it is just a warning makes it somewhat insignificant issue, considering that you still can use firefox.

Additionally, /usr/lib/x86_64-linux-gnu/gtk-3.0/modules/libappmenu-gtk-module.so is a shared object which is meant to be used by multiple applications and it is not specific to firefox. Removing it may hide the warning, but it's probably not the best idea since this is a shared object and other applications may rely on it for proper working.

You can still submit a bug report with link to this answer to firefox developers as warning appears after initial negotiation method, whereas firefox probably could try other methods first before issuing the warning, however I wouldn't count on this being high-priority issue for the developers and likely it will be left with WONTFIX status.