gchq/CyberChef · error · OperationError

Invalid file type.

Error message

Invalid file type.

What it means

Top-of-run guard in Image Filter: isImage(input) must return true before Jimp is invoked. Identical in intent to error 412 - the buffer's magic bytes must match a known raster image type.

Source

Thrown at src/core/operations/ImageFilter.mjs:48

        this.presentType = "html";
        this.args = [
            {
                name: "Filter type",
                type: "option",
                value: ["Greyscale", "Sepia"],
            },
        ];
    }

    /**
     * @param {ArrayBuffer} input
     * @param {Object[]} args
     * @returns {byteArray}
     */
    async run(input, args) {
        const [filterType] = args;
        if (!isImage(input)) {
            throw new OperationError("Invalid file type.");
        }

        let image;
        try {
            image = await Jimp.read(input);
        } catch (err) {
            throw new OperationError(`Error loading image. (${err})`);
        }
        try {
            if (isWorkerEnvironment())
                self.sendStatusMessage(
                    "Applying " +
                        filterType.toLowerCase() +
                        " filter to image...",
                );
            if (filterType === "Greyscale") {
                image.greyscale();
            } else {

View on GitHub (pinned to 4290ea7539)

Solutions

1. Confirm the input is a complete raster image (PNG/JPEG/GIF/BMP/WebP).
2. Decode base64/hex input first.
3. Reject empty buffers before invoking.
4. Rasterise vector formats (SVG/PDF) beforehand.

Example fix

// before
op.run(svgString, ["Greyscale"]);
// after: rasterise then filter
op.run(pngBuffer, ["Greyscale"]);

import { isImage } from "../lib/FileType.mjs";
function assertFilterImageInput(buf) {
  if (!isImage(buf)) throw new Error('Input is not a recognised image type');
}

function isFilterImageInput(buf) {
  return buf instanceof ArrayBuffer ? isImage(new Uint8Array(buf)) : !!isImage(buf);
}

try {
  result = await filter.run(buf, [filterType]);
} catch (e) {
  if (e instanceof OperationError && /Invalid file type/.test(e.message)) {
    return null;
  }
  throw e;
}

When it happens

Trigger: Non-image ArrayBuffer, empty buffer, SVG, undecoded base64/hex, or a buffer whose header was stripped by a preceding operation.

Common situations: Wrong input into the filter op; forgot to From Base64; chained after an op that returned text; dropped a PDF expecting raster handling.

Related errors

• Invalid file type.
• Invalid file type.
• Invalid file type.
• Invalid file format.
• Invalid file type.

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/c509a4a780832bdd. Report an issue: GitHub.