Input nodes are a special type of node that creates a dynamic slot in your graph, allowing for any input to be connected once your Graph is used in another context. Unlike Output Nodes, you have to explicitely place either a Color, Grayscale or Value input. It is not possible to create your own "agnostic" inputs that change type depending on what is connected to them.
Inputs are only used when you want to base your Graph or Node Instance's result on an external input, for example when creating an Instance or a Filter for Painter.
See the documentation:
https://docs.substance3d.com/sddoc/input-172825359.htmlI've used Input Nodes for helpers in Painter and they would act as a slot where I could drop in a resource. For the purpose of having a solid fill you would use the Uniform Color node.
The reason this is causing a problem is because you put a value in the range beyond black:
If you did move it all the way to black it wouldn't give you the error anymore but you should be using Uniform Color for solid fills unless you want to actually plug in something there.
This is why the other part in your graph doesn't throw the error:
But again, you should be using the Uniform Color node unless you need to have a slot.
If you want to change the range you can even expose the range and have access to that in Painter.
https://docs.substance3d.com/sddoc/uniform-color-172825339.htmlIf you wanted to make that node take in an input itself you could make your graph work:
Then in Painter you'll see an option to plug something in:
I can make a fill and anchor it to show an example:
I think you just got confused and used the wrong node.
