What does "Gtk-ERROR **: GTK+ 2.x symbols detected." mean?

Question

When starting gparted, it crashes with the error:

Gtk-ERROR **: GTK+ 2.x symbols detected.
Using GTK+ 2.x and GTK+ 3 in the same process is not supported

I already opened LP bug #1094354 for this.

Searching the internet for this error, I see that almost every Linux distribution suffers from the same issue regarding this GTK+ 2.x/GTK+3 error for various other GTK-based programs too, e.g. gedit, gwibber, canberra-gtk, etc...

The GTK developers are claiming that it's not a GTK bug. Yet, no one on all the sites I've Googled has come up with an answer as to what this error message actually means.

What is going on in a program to cause this error? And what does this error mean in detail?

Solution

It means that you are running an application which attempted to load the symbols from the GTK+ 2.x libraries, as well as the 3.x libraries. This is a problem, because there are several conflicting symbols in the libraries.

It is not a GTK+ bug, as GTK+ is doing the right thing by exiting early with a failure. If it didn't, you would most likely get very unpredictable behavior. In many cases, it is an issue with plug-ins, where the main app has been ported to GTK+ 3.x, but all the plug-ins haven't, and some people might still have older plug-ins installed, or similar.

Comments

[gertvdijk]

Can you reproduce this in a clean installation? I believe this is a result of earlier installations from source, now mixed up with Ubuntu packages updates on top of it in an odd way.