gchq/CyberChef · error · OperationError

Please enter a valid image file.

Error message

Please enter a valid image file.

What it means

Thrown by 'View Bit Plane' when isImage(input) returns false. The operation expects an ArrayBuffer containing a recognised image; if the magic bytes / content type are not a supported image format it aborts before attempting Jimp parsing.

Source

Thrown at src/core/operations/ViewBitPlane.mjs:53

                type: "option",
                value: COLOUR_OPTIONS,
            },
            {
                name: "Bit",
                type: "number",
                value: 0,
            },
        ];
    }

    /**
     * @param {ArrayBuffer} input
     * @param {Object[]} args
     * @returns {ArrayBuffer}
     */
    async run(input, args) {
        if (!isImage(input))
            throw new OperationError("Please enter a valid image file.");

        const [colour, bit] = args;
        let parsedImage;
        try {
            parsedImage = await Jimp.read(input);
        } catch (err) {
            throw new OperationError(`Error loading image. (${err})`);
        }

        const width = parsedImage.bitmap.width,
            height = parsedImage.bitmap.height,
            colourIndex = COLOUR_OPTIONS.indexOf(colour),
            bitIndex = 7 - bit;

        if (bit < 0 || bit > 7) {
            throw new OperationError(
                "Error: Bit argument must be between 0 and 7",
            );

View on GitHub (pinned to 4290ea7539)

Solutions

1. Provide a supported image file (PNG/JPEG/BMP/GIF etc.) as an ArrayBuffer.
2. Ensure the upstream operation outputs bytes (e.g. 'From Base64' or a file input) rather than text.
3. If the source is a different format, convert it to PNG first.

if (!isImage(input)) throw new Error("Input is not a recognised image format");

function isImage(buf) { return buf instanceof ArrayBuffer && /\x89PNG|\xff\xd8\xff|GIF8|BM/.test(String.fromCharCode(...new Uint8Array(buf.slice(0,4)))); }

When it happens

Trigger: Passing non-image bytes (text, a zip, raw bytes), an unsupported image format, or a truncated image header. Input must arrive as an ArrayBuffer whose magic bytes pass CyberChef's isImage check.

Common situations: Forgetting to switch the input type, piping a string/text operation output directly into View Bit Plane, or supplying a file format Jimp/isImage does not support (e.g. certain TIFF/HEIC variants).

Related errors

• Error opening image. (${err})
• Invalid file type.
• Please enter a valid image file.
• Invalid file type.
• Error normalising image. (${err})

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/5d3db393da22961b. Report an issue: GitHub.