troubleshooting

# ComfyUI Troubleshooting Guide > Render completes but looks WRONG (artifacts, wrong subject/pose/color, a > ControlNet/mask/LoRA not taking, a refiner degrading it)? That's not an error. > Use the debug-render skill (`list_packs` with `action: "skill_read"`, > `name: "debug-render"`) to localize the bad stage with run-to-node > (`panel_run` `to_node_id`) by previewing intermediate steps. This guide is for > runs that fail with an error, OOM, or missing node. ## Error Diagnosis Strategy When a workflow fails, follow this approach: 1. Get the error. Use `get_history(action="diagnose")` to retrieve the execution result with the full traceback, plus any missing models/nodes 2. Check logs. Use `get_system_stats (action:"logs")` with keyword filters like `"error"`, `"warning"`, `"traceback"` 3. Identify the failing node. The history response includes the `node_id` and `node_type` that failed 4. Cross-reference inputs. Use `create_workflow (action:"node_info")` to verify the failing node's expected input schema 5. Check models. Use `list_local_models` to verify all referenced model files exist ## Out of Memory (OOM) ### Error Pattern ``` torch.cuda.OutOfMemoryError: CUDA out of memory. Tried to allocate X MiB. GPU 0 has a total capacity of 24.00 GiB of which X MiB is free. ``` Or: ``` RuntimeError: CUDA error: out of memory ``` ### Root Cause The GPU does not have enough VRAM to hold the model weights, intermediate tensors, and latent images at the same time. Common trig...