gchq/CyberChef · error · OperationError

Number of vertical bins must be greater than 0

Error message

Number of vertical bins must be greater than 0

What it means

Thrown by Heatmap chart when the 'Number of vertical bins' argument (vBins, args[2]) is less than or equal to zero. The bin count drives the matrix resolution, so a non-positive value makes the chart unrenderable and is rejected before any data is parsed.

Source

Thrown at src/core/operations/HeatmapChart.mjs:107

    /**
     * Heatmap chart operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {html}
     */
    run(input, args) {
        const recordDelimiter = Utils.charRep(args[0]),
            fieldDelimiter = Utils.charRep(args[1]),
            vBins = args[2],
            hBins = args[3],
            columnHeadingsAreIncluded = args[4],
            drawEdges = args[7],
            minColour = args[8],
            maxColour = args[9],
            dimension = 500;
        if (vBins <= 0) throw new OperationError("Number of vertical bins must be greater than 0");
        if (hBins <= 0) throw new OperationError("Number of horizontal bins must be greater than 0");

        let xLabel = args[5],
            yLabel = args[6];
        const { headings, values } = getScatterValues(
            input,
            recordDelimiter,
            fieldDelimiter,
            columnHeadingsAreIncluded
        );

        if (headings) {
            xLabel = headings.x;
            yLabel = headings.y;
        }

        const document = new nodom.Document();
        let svg = document.createElement("svg");

View on GitHub (pinned to 4290ea7539)

Solutions

1. Set the Number of vertical bins argument to a positive integer (default is 25).
2. Choose a bin count appropriate to data density (typically 5-100).
3. If building the recipe programmatically, guard args[2] > 0 before passing.

Example fix

// before
chart.run(input, ["\n", ",", 0, 25, true]);
// after
chart.run(input, ["\n", ",", 25, 25, true]);

function assertVerticalBins(vBins) {
  if (!Number.isFinite(vBins) || vBins <= 0 || !Number.isInteger(vBins)) {
    throw new RangeError(`Vertical bins must be a positive integer, got ${vBins}`);
  }
}

function isValidVerticalBins(v) {
  return Number.isInteger(v) && v > 0;
}

try {
  html = heatmap.run(input, args);
} catch (e) {
  if (e instanceof OperationError && /vertical bins/i.test(e.message)) {
    args[2] = 25; // fall back to default
    html = heatmap.run(input, args);
  } else throw e;
}

When it happens

Trigger: Setting the vertical bins argument to 0 or a negative number; a recipe/JSON config that defaults an unset numeric field to 0; programmatic invocation passing args[2] <= 0.

Common situations: Defaulting a numeric arg to 0 in a generated recipe; user clearing the field and the UI coercing empty to 0; copying a recipe that used a placeholder.

Related errors

• Number of horizontal bins must be greater than 0
• Invalid block cipher mode: ${mode}
• Invalid ciphertext length: ${originalLength} bytes. Must be
• 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/6f076fab331b9437. Report an issue: GitHub.