ComfyUI quietly shipped v0.41.3 to fix Flux 3 Klein workflows — update guide
Mad4reds · reddit · 2026-10-19
A Reddit user pieced together the timeline of ComfyUI's fix for Flux 3 Klein support issues, criticizing the team's poor communication — the fix was only acknowledged on GitHub by Black Forest Labs, with nothing on the official blog:
- Oct 15: Klein launched with ComfyUI support in v0.41.0 (PR #17064), but the initial workflow had errors. That evening, BFL's Stephen said on Hugging Face a fix was coming, and v0.41.2 shipped corrected workflows shortly after.
- Oct 17: BFL updated the recommended workflow again, requiring v0.41.3 and adding a dedicated prompt upsampler, flux-3-image-klein-pup (a Qwen3.5-9B fine-tune, 9.75GB INT8 or full 18GB), with 2K generation recommended to match training conditions. Model weights are unchanged.
How to update: v0.41.3 never got a formal GitHub Release (patch tags live on master only), so just move to v0.42.1, the latest release. Portable users run update\updatecomfyui.bat; Git installs use git pull + pip install; Desktop users check for updates in settings (Desktop may lag on stable releases).
Related event: BFL and ComfyUI ship fixes for FLUX 3 Klein launch issues(4 posts)→
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