After trying the new in-development of 17.10 ubuntu version, I see a strange message with my SDL2 based program:

process 27418: arguments to dbus_type_is_basic() were incorrect, assertion "dbus_type_is_valid (typecode) || typecode == DBUS_TYPE_INVALID" failed in file ../../../dbus/dbus-signature.c line 322.
This is normally a bug in some application using the D-Bus library.
type unknown isn't supported yet in dbus_message_append_args_valist

It seems SDL_Init() creates it. I can demonstrate even with a very simple C program only has this call in main: SDL_Init(SDL_INIT_EVERYTHING);

This ubuntu version ships 2.0.6 SDL, but as far as I can see, my programs compiled on the previous system (thus using 2.0.5 SDL) now produces the same on the new system the same way:

process 27418: arguments to dbus_type_is_basic() were incorrect, assertion "dbus_type_is_valid (typecode) || typecode == DBUS_TYPE_INVALID" failed in file ../../../dbus/dbus-signature.c line 322.
This is normally a bug in some application using the D-Bus library.
type unknown isn't supported yet in dbus_message_append_args_valist
SDL version: (hg-11524:8df7a59b5528) compiled with 2.0.5, used with 2.0.6 on platform Linux

(the "SDL: ..." line is already printout of my program)

It's true that I haven't seen any negative impact yet of this message other than being annoying what it can be. Surely, it can be an ubuntu problem, especially because it's a development phase distro now. dbus version seems to be: 1.10.22

I'm not sure if it's help to mention, but only using google I've found this, which seems to be related or whatever:

https://github.com/spurious/SDL-mirror/commit/be62ae89101bf2be5b7ddedc31716deebfbf2ed9

At least it seems this is the place where DBUS_TYPE_INVALID were introduced what dbus is angry for now. Surely, I don't know dbus, and not even SDL internally, so I am just guessing here, sorry if I am wrong here.