Whenever I try to launch the Witcher 3 with my GOG client, it always instantly crashes sometimes showing a black screen. This has never happened before I installed 1.05 along with all the DLCs. Can someone please help me?

Some fixes are causing other problems,try the game without using Galaxy.

Thanks to Tino5555 I can now start my game :)

SOLUTION:

its possible to run dx11 game on dx10 graphics card
you have to download the Microsoft Windows SDK for Windows 7 or Windows 8 and you have to install this on your pc

after installing this you have to search the dxcpl.exe from your windows searchbox
in dxcpl.exe you have to add witcher3.exe (edit list --> add --> your directory to witcher3.exe)
below, activate the "force WARP" and set the level 11_1

after that, I was able launch and start the game