I’m trying to get Union Flux ControlNet working properly in my ComfyUI setup but running into some issues. Has anyone successfully implemented this workflow before?
I’ve been experimenting with different node configurations but can’t seem to get the right combination working. The documentation isn’t super clear about which specific nodes need to be connected and in what order.
What I’m looking for is a working example that shows the complete node setup from start to finish. I’ve tried various approaches but keep getting errors or unexpected results.
If you have a functional workflow, could you share the node arrangement and any specific settings that worked for you? Also wondering about any particular model requirements or preprocessing steps that might be necessary.
Any help would be really appreciated since I’ve been stuck on this for a while now.
You’re probably hitting a control image format issue. Union Flux is picky about dimensions and channels - way more than regular ControlNet.
I had this same problem last month. Fix: make sure your control images match your target output resolution exactly. Don’t let ComfyUI do the scaling - handle it beforehand.
For the workflow, you need three paths that merge at sampling. Input image → preprocessor → Union ControlNet node. Text prompt → normal Flux conditioning. Sampler takes both streams.
The Union ControlNet node is the tricky bit. Start with control_mode set to “balanced”, then tweak from there. I use scale_soft_weights at 1.0 with global_average_pooling enabled.
Make sure you’ve got the actual Union ControlNet weights - they’re different from regular Flux ControlNet files. Union models are around 2.5GB if you want to double-check.
Still getting errors? Load a basic Flux workflow without any ControlNet first. Once that’s working, add Union ControlNet nodes one at a time. Makes it easier to spot where things break.
Manual ComfyUI workflows break constantly when updates hit. I’ve rebuilt the same Union Flux setup three times in one month - learned my lesson the hard way.
So I automated everything instead. My system grabs the right models, checks compatibility, handles preprocessing, and connects all the nodes automatically.
The game-changer is batch processing and switching between ControlNet types. Manual setup means reconfiguring everything every single time. Automation just handles it - Union Flux, regular ControlNet, depth maps, whatever.
I built workflows that watch VRAM usage, adjust settings for your hardware, and retry failed generations with different parameters. No more babysitting or losing work to random crashes.
Best part? Version control. When ComfyUI updates break your workflow, automation rebuilds everything in minutes instead of hours.
I had the same issues when I started with Union Flux ControlNet. The breakthrough was understanding that image preprocessing happens completely outside the main workflow. Run your control image through the right preprocessor first - Canny, depth, whatever you’re using. Save that processed image and load it fresh into ComfyUI as your control input. Most tutorials skip this part. Memory allocation got me too. Union ControlNet eats VRAM like crazy - had to increase my settings in the extra model options. Also check your checkpoint versions are compatible. I spent hours troubleshooting before realizing my Flux model was outdated. Once preprocessing is sorted, the workflow’s simple. Control image → Union ControlNet loader, model connects normally, conditioning flows through fine.
Been there with Union Flux ControlNet - those node connections are brutal to set up manually.
Skip the ComfyUI headaches and automate the whole thing. Build a system that handles node connections, model loading, and preprocessing automatically.
I’ve watched teams waste weeks getting workflows stable, then lose it all when switching machines. Smart move? Automate your entire pipeline so it sets up the same way every time.
Create workflows that handle model requirements, arrange nodes, and recover from errors automatically. No more manual debugging or trying to remember settings.
Bonus: the automation can monitor everything, restart when stuff breaks, and handle batch processing for multiple images.
the trick that saved me was downgrading comfyui manager first. newer builds have conflicts with union flux nodes that nobody mentions. also make sure you’re using the union version of the controlnet apply node, not the regular one. took me forever to figure that out.
Union Flux ControlNet is all about nailing the preprocessor chain before it reaches the main node. Most people skip the intermediate conditioning steps and that’s what causes those weird errors. Here’s what works for me: connect your Flux model loader to a proper conditioning node, then route it through the Union ControlNet apply node. The part everyone screws up is the strength values - I use 0.8 for most stuff but you’ll need to tweak it depending on your input. Also, make sure you’ve got the right Union ControlNet model file. There’s different versions out there and some don’t play nice with certain Flux checkpoints. I stick with the official release from the Flux team instead of community versions. One last thing - check your VAE decode settings. Union ControlNet gets picky about how latents are processed at the end.