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Diagnostic Knowledge Base & Crash Patch Directory|Community Validated Fixes

ComfyUI MOSS-Image Troubleshooting & Error Fix Guide

Instant solutions for common MOSS-Image startup crashes. Find tested fixes for CUDA Out of Memory (OOM) on 8GB/12GB graphics cards, missing native layout nodes, and Qwen3.5-9B text encoder tokenizer errors.

Updated for ComfyUI Native Release
Symptom

Red node boxes in ComfyUI canvas showing 'Node not recognized' or 'Missing Custom Node' upon dragging workflow PNG.

Root Cause

Your ComfyUI installation is running an older commit before native MOSS-Image PR integration, or custom nodes were placed in the wrong folder.

Step-by-Step Resolution:
  1. Navigate to your ComfyUI root directory in terminal.
  2. Run `git pull` to fetch the latest upstream nodes and PR patches.
  3. If you are using manual custom nodes, clone `ComfyUI-MOSS-Image` into `ComfyUI/custom_nodes/`.
  4. Restart ComfyUI backend server.
Terminal Fix CommandRun in ComfyUI directory
cd ComfyUI && git pull && pip install -r requirements.txt
Symptom

Terminal crashes with `torch.cuda.OutOfMemoryError: Tried to allocate 4.20 GiB (GPU 0; 8.00 GiB total capacity)` during prompt encoding.

Root Cause

Qwen3.5-9B is a 9-billion parameter model. In full BF16 precision, loading it alongside the 10.2GB MOSS diffusion weights exceeds 18GB VRAM.

Step-by-Step Resolution:
  1. Launch ComfyUI with `--lowvram` flag: this forces automatic CPU offloading for text encoding.
  2. Replace the 18GB BF16 text encoder with the FP8 quantized version (`qwen_3.5_9b_fp8.safetensors`, only 4.8GB).
  3. Enable `--cpu-vae` to decode the final image in system RAM rather than GPU VRAM.
  4. If running on an 8GB card and encountering extreme slowdowns, consider cloud GPU instances.
Terminal Fix CommandRun in ComfyUI directory
python main.py --lowvram --fp8_e4m3fn --cpu-vae
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If you are encountering frequent memory crashes or slow generation on cards with ≤ 12GB VRAM, use these startup parameters:

python main.py --lowvram --fp8_e4m3fn --cpu-vae --preview-method auto
--lowvramAutomatically offloads the 9B Qwen text encoder from GPU to system RAM once prompt conditioning finishes.
--fp8_e4m3fnLoads diffusion cross-attention linear projections in 8-bit float, cutting peak VRAM by 35%.
--cpu-vaeDecodes the final 1024x1024 latent canvas in system RAM to avoid the final step OOM crash.
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