gchq/CyberChef · error · OperationError

Unsupported Mode: (${mode})

Error message

Unsupported Mode: (${mode})

What it means

Thrown by GenerateImage when the 'mode' argument is not one of the recognized pixel-format keys: Greyscale, RG, RGB, RGBA, or Bits. The operation maps each mode to a bytes-per-pixel value and refuses unknown modes before processing input. This guards the downstream pixel-writing loop from an out-of-range switch fallthrough.

Source

Thrown at src/core/operations/GenerateImage.mjs:84

    /**
     * @param {byteArray} input
     * @param {Object[]} args
     * @returns {ArrayBuffer}
     */
    async run(input, args) {
        const [mode, scale, width] = args;
        input = new Uint8Array(input);

        const bytePerPixelMap = {
            Greyscale: 1,
            RG: 2,
            RGB: 3,
            RGBA: 4,
            Bits: 1 / 8,
        };

        if (!Object.hasOwn(bytePerPixelMap, mode)) {
            throw new OperationError(`Unsupported Mode: (${mode})`);
        }

        const bytesPerPixel = bytePerPixelMap[mode];

        if (bytesPerPixel > 0 && input.length % bytesPerPixel !== 0) {
            throw new OperationError(
                `Number of bytes is not a divisor of ${bytesPerPixel}`,
            );
        }

        const height = Math.ceil(input.length / bytesPerPixel / width);
        const image = new Jimp({ width, height });

        if (isWorkerEnvironment())
            self.sendStatusMessage("Generating image from data...");

        if (mode === "Bits") {
            let index = 0;

View on GitHub (pinned to 4290ea7539)

Solutions

1. Set the mode argument to one of: Greyscale, RG, RGB, RGBA, or Bits.
2. If building recipes in code, validate that mode is in the allowed set before invoking the operation.
3. Check the operation's ingList/config for the current list of supported mode values.

Example fix

// before
args[0] = "CMYK";
// after
args[0] = "RGBA"; // one of Greyscale|RG|RGB|RGBA|Bits

const VALID_MODES = ["Greyscale", "RG", "RGB", "RGBA", "Bits"];
if (!VALID_MODES.includes(mode)) {
  // reject before calling GenerateImage
}

function isImageMode(m) {
  return ["Greyscale", "RG", "RGB", "RGBA", "Bits"].includes(m);
}

When it happens

Trigger: Passing a mode string not present in bytePerPixelMap — e.g. 'CMYK', 'BGR', 'GRAY', a typo like 'RBGA', or a localized/case variant. Also triggered if args[0] is undefined or null because the recipe was constructed programmatically without a mode.

Common situations: Programmatically building a recipe and forgetting to set the mode ingredient, or a UI dropdown change that submits a stale enum value after an operation update.

Related errors

• Invalid length type
• Invalid UUID version
• Unknown granularity value: ${granularity}
• Error: Bit argument must be between 0 and 7
• Invalid secret. The input must be a valid base32 string (cha

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/a73d46cdbe0c38b3. Report an issue: GitHub.