Just for info: Again using Win7 / Gimp 2.8.20
I can get that error when the image is: Tons de cinzento - grayscale Not sure about the curve type liso - straight ? There is a difference in the number of points between smooth and freehand but af far as I can tell both work.
Here the results from a mix of images. RGB and RGB desaturated are processed. The single grayscale fails.
I am sure Ofnuts will fix it for you.
I can get that error when the image is: Tons de cinzento - grayscale Not sure about the curve type liso - straight ? There is a difference in the number of points between smooth and freehand but af far as I can tell both work.
Here the results from a mix of images. RGB and RGB desaturated are processed. The single grayscale fails.
I am sure Ofnuts will fix it for you.