CUDA-GDB Error message

I’m trying to step through my code with cuda-gdb and I’m getting this error message all of the sudden.

(cuda-gdb) n
Error: Failed to get warp state (dev=0, sm=0, wp=1), error=CUDBG_ERROR_UNKNOWN_FUNCTION(0x3).

(cuda-gdb) n
Cannot execute this command while the selected thread is running.

Previously I’ve ran the same code with the debugger with no problem before. What is this message trying to tell me?