# Troubleshooting

## CUDA toolkit does not contain XXX

This means that you have an incomplete or missing CUDA toolkit, or that not all required parts of the toolkit are discovered. Make sure the missing binary is present on your system, and fix your CUDA toolkit installation if it isn't. Else, if you installed CUDA at a nonstandard location, use the CUDA_HOME environment variable to direct Julia to that location.

Note that this error only occurs when you're not using the automatic, artifact-based installation (e.g., because you set JULIA_CUDA_USE_BINARYBUILDER=false). This is not a recommended set-up, and it is possible that local CUDA discovery will be removed at some point in the future.

## UNKNOWN_ERROR(999)

If you encounter this error, there are several known issues that may be causing it:

• a mismatch between the CUDA driver and driver library: on Linux, look for clues in dmesg
• the CUDA driver is in a bad state: this can happen after resume. Try rebooting.

Generally though, it's impossible to say what's the reason for the error, but Julia is likely not to blame. Make sure your set-up works (e.g., try executing nvidia-smi, a CUDA C binary, etc), and if everything looks good file an issue.

Check and make sure the NVSMI folder is in your PATH. By default it may not be. Look in C:\Program Files\NVIDIA Corporation for the NVSMI folder - you should see nvml.dll within it. You can add this folder to your PATH and check that nvidia-smi runs properly.