Ollama / Ollama
Ollama CUDA Backend Crash on RTX 50-Series (Blackwell) with Q4_K_M Models
Fix Ollama ggml_cuda_cpy crash on RTX 50-series Blackwell GPUs Includes evidence for Ollama troubleshooting demand.
- Category
- Ollama
- Error signature
ggml_cuda_cpy: unsupported type combination (q4_K to q4_K)- Quick fix
- Compare the failing environment with a known working setup, then change one configuration value at a time.
- Updated
What this error means
ggml_cuda_cpy: unsupported type combination (q4_K to q4_K) is a Ollama failure pattern reported for developers trying to fix ollama ggml_cuda_cpy crash on rtx 50-series blackwell gpus. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.
Why this happens
GitHub issue (updated 2026-05-03). Loading any Q4_K_M GGUF model crashes on RTX 50-series (Blackwell, compute 12.0). ggml_cuda_cpy unsupported type combination. Runner exits with 500. Workaround: force Vulkan backend via OLLAMA_LLM_LIBRARY.
Common causes
- Users with RTX 50-series (Blackwell, compute 12.0) GPUs cannot run any Q4_K_M GGUF models in Ollama. The CUDA backend fails immediately with ‘unsupported type combination’ error. Affects the latest GPU generation with no workaround except forcing Vulkan backend.
- GitHub issue (updated 2026-05-03). Loading any Q4_K_M GGUF model crashes on RTX 50-series (Blackwell, compute 12.0). ggml_cuda_cpy unsupported type combination. Runner exits with 500. Workaround: force Vulkan backend via OLLAMA_LLM_LIBRARY.
Quick fixes
- Confirm the exact error signature matches
ggml_cuda_cpy: unsupported type combination (q4_K to q4_K). - Check the Ollama account, local tool state, and provider configuration involved in the failing workflow.
- Compare the failing environment with a known working setup, then change one configuration value at a time.
Platform/tool-specific checks
- Verify the command, editor, extension, or API client that produced the error.
- Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
- Avoid deleting credentials, local model data, or project settings until the failing scope is clear.
Step-by-step troubleshooting
- Capture the exact error message and the command, editor action, or request that triggered it.
- Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
- Review the source evidence below and compare it with your environment.
- Apply one change at a time and rerun the smallest failing action.
- Keep the working fix documented for the team or deployment environment.
How to prevent it
- Keep provider/tool configuration documented.
- Record non-secret diagnostics such as tool version, provider name, model name, and command path.
- Add a lightweight check before CI or production workflows depend on the tool.
Sources checked
Evidence note: GitHub issue (updated 2026-05-03). Loading any Q4_K_M GGUF model crashes on RTX 50-series (Blackwell, compute 12.0). ggml_cuda_cpy unsupported type combination. Runner exits with 500. Workaround: force Vulkan backend via OLLAMA_LLM_LIBRARY.
Related errors
- Ollama GGML_ASSERT failed on CUDA
- Ollama Blackwell GPU compatibility
FAQ
What should I check first?
Start with the exact ggml_cuda_cpy: unsupported type combination (q4_K to q4_K) text and the smallest action that reproduces it.
Can I ignore this error?
No. Treat it as a failed Ollama workflow until the root cause is understood.
Is this guaranteed to have one fix?
No. The imported evidence supports the troubleshooting path above, but tool behavior can vary by account, plan, version, provider, and local configuration.
How do I know the fix worked?
Rerun the same command, editor action, or request. The fix is working when that action completes without ggml_cuda_cpy: unsupported type combination (q4_K to q4_K).