🖼️ 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.

Recommended Order

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.

Useful Links

• Github Issue