gchq/CyberChef · error · OperationError

Invalid file type.

Error message

Invalid file type.

What it means

Thrown by GenerateQRCode.present() when the format is PNG and isImage() cannot identify the QR code buffer as a recognized image format. present() runs on the operation's PNG output, so this means the PNG bytes were not recognized — implying truncated or corrupted output from the encoding step.

Source

Thrown at src/core/operations/GenerateQRCode.mjs:83

        const [format, size, margin, errorCorrection] = args;

        return generateQrCode(input, format, size, margin, errorCorrection);
    }

    /**
     * Displays the QR image using HTML for web apps
     *
     * @param {ArrayBuffer} data
     * @returns {html}
     */
    present(data, args) {
        if (!data.byteLength && !data.length) return "";
        const dataArray = new Uint8Array(data),
            [format] = args;
        if (format === "PNG") {
            const type = isImage(dataArray);
            if (!type) {
                throw new OperationError("Invalid file type.");
            }

            return `<img src="data:${type};base64,${toBase64(dataArray)}">`;
        }

        return Utils.arrayBufferToStr(data);
    }

}

export default GenerateQRCode;

View on GitHub (pinned to 4290ea7539)

Solutions

1. Ensure the QR code input string is non-empty and within the QR capacity for the selected error-correction level.
2. Use SVG format to bypass the image-type check if PNG encoding is problematic.
3. Verify the buffer has PNG magic bytes (\x89PNG) before present().

const PNG_MAGIC = [0x89, 0x50, 0x4e, 0x47];
const isPng = data.length >= 4 && PNG_MAGIC.every((b, i) => data[i] === b);
if (format === "PNG" && !isPng) {
  // use SVG format or fix the upstream QR generation
}

function looksLikePng(buf) {
  return buf.length >= 4 && buf[0] === 0x89 && buf[1] === 0x50 && buf[2] === 0x4e && buf[3] === 0x47;
}

When it happens

Trigger: The QR encoder returned a non-PNG or malformed buffer, or present() receives data that has been altered between run() and present(). SVG format bypasses this check.

Common situations: An empty/failed QR generation upstream, or chaining through an operation that corrupts bytes before present().

Related errors

• Invalid file type.
• Invalid file type.
• Invalid file type.
• No padding requested but input is not a ${blockSize}-byte mu
• Unknown padding type: ${padding}

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/98716d7235b67f06. Report an issue: GitHub.