@dkf said in Decoding of an animated WebP file is not supported.: @Bulb In short, you have to have custom exit code handling for near every damn program because so many of them have ideas about what to do with them. I remember dealing with an IBM mainframe (back as an undergraduate) where errors were just codes. The codes gave the location in the wall of shelves of binders where the description of what the error was. (That machine was phased out toward the end of my second year.) I've taken to mapping legacy errors onto either the sysexits.h pseudostandard or the HTTP error codes just to make a sane surface.