ComfyUI Troubleshooter

Diagnoses and resolves ComfyUI issues across four categories: server errors, workflow errors, quality issues, and performance problems.

Diagnosis Process

Step 1: Classify the Error

Category	Symptoms	First Check
Server	Connection refused, timeouts, crashes	Is ComfyUI running? Check `/system_stats`
Workflow	Node errors, missing inputs, type mismatches	Validate workflow against inventory
Quality	Artifacts, wrong identity, blurry output	Check settings (CFG, weights, resolution)
Performance	OOM, slow generation, VRAM errors	Check VRAM usage, model sizes

Step 2: Gather Context

Collect before diagnosing:

Error message (exact text)
Workflow being executed (or description)
Models involved (checkpoint, LoRA, ControlNet, etc.)
Settings (CFG, steps, resolution, sampler)
Hardware (from foundation/hardware-profile.md)
Inventory (from state/inventory.json)

Step 3: Match Error Pattern

See references/troubleshooting.md for the full error database.

Quick Fix Reference

Top 10 Most Common Errors

1. "CUDA out of memory" → Use FP8: --fp8_e4m3fn-unet → Enable tiled VAE → Reduce resolution → Restart ComfyUI (clears fragmentation)

2. "Node type not found: {name}" → Install the custom node package via ComfyUI-Manager → Check comfyui-inventory node-to-package mapping

3. "Expected scalar type BFloat16 but found Float" → Precision mismatch. Add --force-fp16 or use matching precision nodes

4. Burned/overexposed faces → Lower CFG to 4-5 (InstantID) → Reduce identity method weight → Add noise to negative embeds (35%)

5. "No model found at path" → Check filename spelling (exact match required) → Verify file is in correct subdirectory → Run inventory scan to confirm

6. Watermark artifacts at 1024x1024 → Use 1016x1016 or 1020x1020 instead

7. Identity doesn't match reference → Use higher quality reference image (clear, front-facing) → Increase IP-Adapter weight to 0.8+ → Verify InsightFace antelopev2 is installed

8. Video flickering → Lower FaceDetailer denoise to 0.3 → Add deflicker post-processing → Increase AnimateDiff context overlap to 4+

9. Queue stuck/not processing → POST /interrupt to cancel → POST /free to unload models → Restart ComfyUI

10. Slow generation → Check if --lowvram is enabled (remove it on RTX 5090) → Use --highvram instead → Update cuDNN to 8800+ → Enable SageAttention for Wan models

Decision Tree: Quality Issues

OUTPUT LOOKS WRONG
    |
    |-- Faces look wrong
    |   |-- Too smooth/plastic → Add skin texture LoRA (0.2-0.4)
    |   |-- Wrong identity → Increase identity weight, check reference quality
    |   |-- Burned/hot → Lower CFG to 4-5, reduce InstantID weight
    |   |-- Deformed → Add "bad anatomy, deformed" to negative
    |   |-- Different every time → Fix seed, add LoRA for consistency
    |
    |-- Colors wrong
    |   |-- Oversaturated → Lower CFG, add "oversaturated" to negative
    |   |-- Washed out → Check VAE is loaded, try different scheduler
    |   |-- Color shift in video → Add color correction post-processing
    |
    |-- Resolution/sharpness
    |   |-- Blurry → Increase steps (25-30), check resolution matches model
    |   |-- Pixelated → Use proper upscaler (4x-UltraSharp), not resize
    |   |-- Artifacts → Lower denoise, check for model corruption
    |
    |-- Composition
    |   |-- Ignoring prompt → Increase CFG slightly, simplify prompt
    |   |-- Extra limbs/objects → Add to negative prompt, use ControlNet
    |   |-- Wrong pose → Add ControlNet OpenPose with reference

Missing Dependency Resolution

When a workflow references something not in inventory:

Missing Custom Node

1. Identify package from class_type (see inventory skill's mapping)
2. Suggest: "Open ComfyUI-Manager → Search → Install {package_name}"
3. Alternative: "cd {ComfyUI}/custom_nodes && git clone {repo_url}"
4. Remind: Restart ComfyUI after installation

Missing Model

1. Look up in references/models.md for download link
2. Provide: exact filename, download URL, target directory
3. For large models (>10GB): suggest HF CLI for reliability
   "huggingface-cli download {repo} {file} --local-dir {path}"

Version Incompatibility

1. Check ComfyUI version vs node package requirements
2. Suggest: "cd {ComfyUI} && git pull" for ComfyUI update
3. Or: pin specific node version if newest breaks things

Escalation

If troubleshooting doesn't resolve the issue:

Check ComfyUI GitHub Issues for known bugs
Check specific node package's Issues
Search r/comfyui for community solutions
Suggest posting in ComfyUI Discord with error details

Reference

references/troubleshooting.md - Full error database with solutions
state/inventory.json - Current installation state
references/models.md - Model download links and paths