Comfyui Troubleshooting

Workflow Execution Failures

Symptoms: comfyui_run_workflow or comfyui_generate_image fails after submission.

Checks:

1. Run comfyui_validate_workflow first to catch structural issues.
2. Check for missing custom nodes — comfyui_list_nodes shows what's installed. If a workflow uses nodes that aren't installed, it will fail.
3. Check connections — a node output index must match what the node actually produces. Use comfyui_get_node_info to verify.
4. Check comfyui_get_queue to see if the job is stuck or if there's a queue backlog.
5. Check comfyui_get_progress with the prompt_id to see which node failed.

Queue Stuck / Job Not Completing

Symptoms: Jobs stay in "running" state indefinitely, or the queue doesn't process.

Checks:

1. Use comfyui_get_queue to see the current state.
2. Use comfyui_interrupt to stop the currently running job.
3. Use comfyui_clear_queue to remove all pending jobs.
4. Check ComfyUI logs for out-of-memory (OOM) errors — large images or complex workflows can exhaust VRAM.

Security Warnings

Symptoms: Tools return messages about "dangerous nodes" or security warnings.

What they mean:

• The MCP server inspects workflows for nodes known to execute arbitrary code, access the network, or read/write files.
• In audit mode (default): warnings are logged but execution proceeds.
• In enforce mode: workflows containing dangerous nodes are blocked.

What to do:

1. Review the flagged nodes. The warning lists which node types were detected and why.
2. If you trust the nodes, you can proceed (audit mode) or add them to an allowlist in config.
3. Use comfyui_audit_dangerous_nodes to scan all installed nodes proactively.
4. Change mode in ~/.comfyui-mcp/config.yaml: security.mode: "audit" or "enforce".

ComfyUI Manager Not Detected

Symptoms: comfyui_search_custom_nodes, comfyui_install_custom_node, and related tools fail or report Manager not available.

Fix: Install ComfyUI-Manager:

1. Navigate to ComfyUI/custom_nodes/
2. git clone https://github.com/ltdrdata/ComfyUI-Manager.git
3. Restart ComfyUI
4. Use comfyui_get_server_features to verify detection.

Model Manager Not Detected

Symptoms: comfyui_search_models, comfyui_download_model fail or report Model Manager not available.

Fix: Install ComfyUI-Model-Manager:

1. Navigate to ComfyUI/custom_nodes/
2. git clone https://github.com/hayden-fr/ComfyUI-Model-Manager.git
3. Restart ComfyUI
4. Use comfyui_get_server_features to verify detection.