Debug Print | Deforum

The most honest debugging tool in this pack: a node that takes any value, prints what it is to the console, and passes it through untouched. Debug Print is the Deforum answer to "I have no idea what my loop is producing," and it works because it's completely generic - the value input is *, so you can drop it on any wire mid-graph without thinking about types.

The trick is that the output isn't a lie: it's the exact same value, so the node is non-invasive. You insert it, read the console, and leave it in - it costs almost nothing and acts as a permanent instrument on that wire.

Where the output actually goes

Here's the thing that confuses everyone the first time: it prints to the ComfyUI console (the terminal you launched ComfyUI from), not anywhere in the browser UI. If you're hunting for the result in the frontend, you'll never find it. On Windows with the portable build that's the run_nvidia_gpu.bat window; on Linux/macOS it's the terminal running python main.py.

The printed line looks like [mylabel]: .... The label input (a STRING you type) is your tag - use descriptive labels per probe or you'll have a wall of undifferentiated lines.

What it prints

It pretty-prints the value in a surprisingly thoughtful way:

• lists, tuples, and dicts get printed recursively (so you can see an ACCUMULATION bundle's contents, not just {"accum": ...})
• strings are quoted, numbers printed plainly
• a torch tensor prints as Tensor[shape] - just the shape, not the data, which is usually what you actually want for a latent
• anything else prints its Python type name

That last bit is the real diagnostic: when a node upstream handed you the wrong thing entirely, Debug Print tells you it's a str when you expected a Tensor, which explains the type error two nodes downstream.

Gotchas

It's console-only, so it's useless if you're running ComfyUI headless without logs. And there's no log-level filtering - every Debug Print fires on every run, and inside a 500-iteration Deforum loop that's 500 lines per probe per node. Don't leave a dozen probes in a loop body while testing a long animation; print one value or print outside the loop.

Installing it

Part of deforum-comfy-nodes, the official Deforum ComfyUI pack. ComfyUI Manager: search "deforum" (comfyui-deforum), install, restart. Manual:

cd ComfyUI/custom_nodes
git clone https://github.com/deforum-art/deforum-comfy-nodes

Restart ComfyUI after. No extra dependencies or model files. Known upgrade hiccup: an orphaned deforum pip package causing load errors; pip uninstall deforum and restart.