When I tried to activate Windows 8 I got the following error message: “Error 0x8007007B The File name, directory name, or volume label syntax is incorrect.”. I was unable to change the Windows key in the Windows Activation GUI. The key was grayed out with no option to edit.
The Fix that worked for me
1. Open a command prompt in administrator mode “Press and hold the Windows button+R”
2. Type slmgr.vbs /ipk (Windows Key) minus the ( ). *** This forces the Windows key to update.
3. Type slmgr.vbs /ato *** This starts the activation
4. If all went well you should be activated at this point.