Did you type those in the powershell?

I had Galaxy installed but uninstalled later. Uninstaller fails to remove Galaxy services from the system, which apparently makes the game fail to start. So, IF you have installed Galaxy, try uninstalling it and then removing leftover services manually.

If you never had Galaxy installed, then this fix won't help.

Once more:
Start cmd in admin mode (right click start button in 8.1, choose command prompt/powershell in admin mode),
then type:
sc.exe delete GalaxyClientService
sc.exe delete GalaxyCommunication

AFter doing that, the game launches for you now?

Yep, playing now.

Yep. I did.

Still no luck.

Still not working for me :(

Same
Faulting application name: witcher3.exe, version: 3.0.0.0, time stamp: 0x5557f2ae
Faulting module name: witcher3.exe, version: 3.0.0.0, time stamp: 0x5557f2ae
Exception code: 0xc0000409
Fault offset: 0x0000000000ddd198
Faulting process id: 0x12ec
Faulting application start time: 0x01d091c7c9e360c5
Faulting application path: C:\GOG Games\The Witcher 3 Wild Hunt\bin\x64\witcher3.exe
Faulting module path: C:\GOG Games\The Witcher 3 Wild Hunt\bin\x64\witcher3.exe
Report Id: 07bd38f0-fdbb-11e4-837c-a088698e6538
Faulting package full name:
Faulting package-relative application ID:

Can you please explain a bit better, I am not so PC literate.

Got it nvm, gonna try to manually patch now and let u know.

What is so hard to understand?

Click start button -> type "cmd" -> right click "cmd.exe" and click "run as administrator"

Type "sc delete GalaxyClientService". Press Enter/Return (or whatever you call it) and repeat with "sc delete GalaxyCommunication". So the GOG background services are removed from you PC. If Galaxy would be a half decent software, the services would have been removed when dleeting the software, but who am I to complain?

I just posted this in another thread, but I also had trouble getting the Witcher 3 to start on Windows 8.1 x64. It just kept crashing.

Rebooted the PC, and for some reason, it ran fine after that. Don't know why, don't care! At least I'm able to play it. :-)

Delete Success

But still game is not launching

Have you tried rebooting PC first? As stated above, for some reason it worked for me.

Gave it a shot, still didn't work.

Ya I think we are in the same boat.

Still not working for me. Let me know if you get it working

Oh, I forgot to mention that I did a manual installation, not via Galaxy, if that makes any difference.

EDIT: I do have the Galaxy beta installed on the same machine though.