If your problem sounds like this:

  • The game doesn't launch, and Windows Event Viewer shows 0xC000001D (Status_Illegal_Instruction).

  • The game worked before, but it stopped launching after an update. 

  • What does error 0xC000001D mean?

Resolution

Error 0xC000001D (Status_Illegal_Instruction) means the CPU is missing a specific hardware instruction set (SSE4.2) that is now required to run the game.

We know it can be an unpleasant surprise when a game suddenly stops working after a patch. If that's exactly what happened to you, it means your old hardware has done an impressive job outperforming official expectations, potentially running the game for years even while falling below our minimum system requirements. However, evolving game technology eventually hits a hard limit, which is exactly what happens with this error.

Because this is a physical limitation of the processor, to put it plainly, there is no software troubleshooting that can resolve it. Reinstalling the game or updating drivers will not bypass the missing architecture. To get back on the Rift, you'll need to upgrade to a machine with a CPU that meets our current minimum system requirements.