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===Error: Couldn't simply reduce colors further. Exporting as opaque.===Even though you have reduced the color depth to 256 prior to trying to save your image as a GIF with a transparent background, it will not succeed. The error indicates Gimp cannot find a a free color slot to create a transparency, which it sees as another color. Resolution: Even though Gif is a 256 color pallet, you must use an index of 255 colors. * Image -> Mode -> Indexed (Maximum number of colors: 255)