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🖼️ Fix Black Image / Video Output in ComfyUI When Using SageAttention

1. Install ComfyUI-KJNodes

  • Open Extensions in ComfyUI.
  • Search for ComfyUI-KJNodes.
  • Install the package.
  • Restart ComfyUI after installation if required.

2. Patch SageAttention Correctly

After loading your model and LoRAs, you must add the node:

Patch Sage Attention KJ

Then select one of the following modes:

  • sageattn_qk_int8_pv_fp16_triton
  • sageattn_qk_int8_pv_fp16_cuda

Important Notes

  • The patch node should be applied after loading the checkpoint/model and LoRAs.
  • Using the wrong SageAttention backend may result in completely black outputs.
  • If one backend does not work on your system, try the other option.
Load Checkpoint
    ↓
Load LoRA(s)
    ↓
Patch Sage Attention KJ
    ↓
Sampler / Generation Nodes

This issue is commonly related to unsupported or unstable SageAttention kernel configurations on certain GPU, CUDA, or PyTorch combinations.

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