gchq/CyberChef · error · OperationError

${err}

Error message

${err}

What it means

Catch-all OperationError thrown by 'VarInt Decode' when the decode loop throws for any reason. The operation expects a byteArray input; the BigInt path reads input[i] & 0x7f per byte. Any non-numeric/NaN byte (e.g. the byteArray contains non-integer or out-of-range entries) makes the BigInt bitwise op throw, which is rewrapped here.

Source

Thrown at src/core/operations/VarIntDecode.mjs:51

     * @param {Object[]} args
     * @returns {number}
     */
    run(input, args) {
        try {
            if (typeof BigInt === "function") {
                let result = BigInt(0);
                let offset = BigInt(0);
                for (let i = 0; i < input.length; i++) {
                    result |= BigInt(input[i] & 0x7f) << offset;
                    if (!(input[i] & 0x80)) break;
                    offset += BigInt(7);
                }
                return result.toString();
            } else {
                return Protobuf.varIntDecode(input).toString();
            }
        } catch (err) {
            throw new OperationError(err);
        }
    }

}

export default VarIntDecode;

View on GitHub (pinned to 4290ea7539)

Solutions

1. Ensure the input is a valid byteArray (run 'From Hex' or 'To ByteArray' first).
2. Confirm each byte is an integer in 0-255.
3. Inspect the wrapped err message in the OperationError for the underlying cause.

Example fix

// before: feeding a hex string directly
// after: convert to bytes first
recipe: [ "From Hex", "VarInt Decode" ]

if (!Array.isArray(input) || input.some(b => typeof b !== "number" || b < 0 || b > 255 || !Number.isInteger(b))) {
  throw new Error("VarInt Decode expects a byteArray of integers 0-255");
}

function isByteArray(data) { return Array.isArray(data) && data.every(b => Number.isInteger(b) && b >= 0 && b <= 255); }

try { return varIntDecode(input); }
catch (err) { throw new Error(`VarInt decode failed: ${err.message}`); }

When it happens

Trigger: Feeding input that is not a clean byteArray of integers 0-255, feeding an empty input that downstream code mishandles, or running the operation with an inputType that produced non-byte values. The catch also wraps any error from the Protobuf fallback path when BigInt is unavailable.

Common situations: Chaining from an operation that emits a string or non-byteArray type into VarInt Decode without a To ByteArray / From Hex step, or malformed varint streams.

Related errors

• ${err}
• Negative values cannot be represented as VarInt
• Schema Error: Schema not defined
• Input Error: ${error}
• Schema ${error}

AI-assisted analysis of gchq/CyberChef@4290ea7539 (2026-08-13). Data as JSON: /api/errors/1016e842d17a1906. Report an issue: GitHub.