FLUX.3 Klein ComfyUI workflow checker
Getting weak or malformed images from a launch-day workflow? Check the JSON against ComfyUI's corrected FLUX.3 Klein examples before changing your setup.
Check your ComfyUI workflow
Select a workflow JSON exported from ComfyUI. It is read in this browser tab and is not sent to our server. This checker compares visible settings with Comfy-Org's corrected examples.
Why this check exists
ComfyUI reported that its first FLUX.3 Klein examples used suboptimal settings. The updated examples enable prompt upsampling by default for text to image, raise Base sampling from 25 to 50 steps, add prompt upsampling to image editing, and use revised model filenames. The Distilled example now uses 16 steps. A copied launch-day workflow can keep the old settings even after ComfyUI itself is updated.
This tool checks the exported graph for those recognizable differences. It does not run the model or diagnose every reason an image looks wrong.
How to fix a flagged workflow
- Update ComfyUI to version 0.41.3 or later, then open a fresh official FLUX.3 Klein template.
- Compare your checkpoint, encoder, VAE, prompt upsampler, steps and CFG with the fresh template for your Base or Distilled variant.
- For text to image, inspect the prompt upsampler switch. It is on by default in the corrected examples, but you may intentionally leave it off for a complete caption.
- Confirm the required model files actually exist in your ComfyUI folders. A JSON check cannot inspect your installation.
Do not rename or replace weights solely because of a warning here. Use the official template and model instructions for your exact variant.
What the result means
Reference settings means the visible values match the checked corrected examples; it does not prove identical routing or guarantee a good image. Review suggested flags a recognizable launch-era pattern or loader type that deserves comparison. Manual judgment means the graph differs from these templates or leaves a setting unreadable. That is not a failure: BF16 and NVFP4 weights, a BF16 prompt upsampler, or intentionally disabled prompt upsampling may be valid. Unknown graph means no standard FLUX.3 Klein UNETLoader was identified.
We compare structure and widget values only. We cannot read your ComfyUI version, installed weights, custom node behavior, prompt quality or resulting image.
Primary sources
- ComfyUI FLUX.3 Klein tutorial and model setup
- ComfyUI official workflow templates, checked at tags v0.11.84 and v0.11.87
- ComfyUI team explanation of the launch-day correction