Getting error when trying to save image that has transparency

I get this error when trying to save the file “libpng: Wrote palette index exceeding num_palette. Error saving frame 1 in the file”.

If I remove any transparency from the sprite it saves just fine. Am I doing something wrong?

I somehow fixed this by coloring the transparent parts and then deleting them. Some sort of bug?

Hi @herravoima, this looks like a critical issue. Related to this conversation:

Changing this to bug category.