Comment 2 for bug 1610183

The same thing was annoing me for the last week....

I'm using Arch+XFCE. So what I found.

Running Plank in terminal were giving me next errors:
[CRITICAL 15:19:27.034831] [System:201] No application is registered as handling this file
[CRIICAL 15:19:27.034867] [System:206] Unable to use application/file '(null)' for execution.

As Plank relies on GVFS i tried
$ gvfs-open trash://
and the command returned error like "No application is registered as handling this file".

It means we need register application (Thunar) to open 'trash://' URI (here I should say, that with Gnome FM installed there were no problems at all) in GVFS.

I found this article https://help.ubuntu.com/community/DefaultFileManager
tl;tr
last chapter "One more way - for "mousemonkeys", like me" told to open "Preffered applications" manager, where Thunar was already set up as default FM, i closed the window, and OMG the Trash docklet opened the trash folder as well as $ gvfs-open trash://. Still works.

Funny .... yeah...