I finally found the cause of the problem! It seems that the DBus service (or the whole DBus) is not running in a UTF-8 locale, thus causing errors in UTF-8 strings.
The workaround is to edit softwareproperties/SoftwareProperties.py and add: path = path.encode('utf-8') in method "def add_key(self, path)" around line 800 before the line: if not os.path.exists(path): This encoding issue may be causing problems in other parts of the program, and other programs. Meanwhile, I found another bug: Dragging and dropping a key file to the list doesn't work, raising an exception: Traceback (most recent call last): File "/usr/lib/python3/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 759, in on_auth_drag_data_received keydata = selection.data.strip() AttributeError: 'SelectionData' object has no attribute 'data' -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1381050 Title: "Import Key File" fails when the path of the file has special characters To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/1381050/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs