apache/cassandra · error · NumberFormatException

does not end in unit

Error message

 does not end in unit 

What it means

FBUtilities.parseHumanReadable parses a human-readable quantity like '10GB' into a numeric value. This NumberFormatException is thrown when the input string does not end with the expected unit suffix (e.g. 'ms', 'KB'). It indicates the value string is missing or has a wrong unit suffix.

Solutions

1. Append the required unit to the value, e.g. change 512 to 512KB
2. Fix the unit spelling/case to exactly match the expected suffix
3. Strip whitespace around the configured value before parsing
4. Change the caller to pass null for unit if the unit should be optional

Example fix

// before: parseHumanReadable(configValue, null, "KiB") where configValue = "1024"
// after:  String configValue = "1024KiB"; // or drop the unit argument

if (value != null && unit != null && !value.trim().endsWith(unit)) throw new IllegalArgumentException("value must end with " + unit);

try { return FBUtilities.parseHumanReadable(s, null, "KB"); } catch (NumberFormatException e) { throw new ConfigurationException("Invalid quantity '" + s + "': " + e.getMessage()); }

When it happens

Trigger: Calling FBUtilities.parseHumanReadable(datum, separator, unit) with a datum whose text does not end with the supplied unit, e.g. parseHumanReadable("10", null, "KB") or "10Mib " with trailing whitespace where unit "KB" is required.

Common situations: Users omit the unit in cassandra.yaml values parsed with a required unit (e.g. column_index_size_in_kb style settings), or include a wrong/misspelled unit.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

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AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/9e172df73a81374b. Report an issue: GitHub.

Appendix: source

Thrown at src/java/org/apache/cassandra/utils/FBUtilities.java:1117

    }

    /**
     * Parse a human-readable value printed using one of the methods above. Understands both binary and decimal
     * modifiers, as well as decimal exponents using the E notation and binary exponents using *2^e.
     *
     * @param datum     The human-readable number.
     * @param separator Expected separator, null to accept any amount of whitespace.
     * @param unit      Expected unit. If null, the method will accept any string as unit, i.e. it will parse the number
     *                  at the start of the supplied string and ignore any remainder.
     * @return The parsed value.
     */
    public static double parseHumanReadable(String datum, String separator, String unit)
    {
        int end = datum.length();
        if (unit != null)
        {
            if (!datum.endsWith(unit))
                throw new NumberFormatException(datum + " does not end in unit " + unit);
            end -= unit.length();
        }

        Matcher m = BASE_NUMBER_PATTERN.matcher(datum);
        m.region(0, end);
        if (!m.lookingAt())
            throw new NumberFormatException();
        double v = Double.parseDouble(m.group(0));

        int pos = m.end();
        if (m.group(2) == null) // possible binary exponent, parse
        {
            m = BINARY_EXPONENT.matcher(datum);
            m.region(pos, end);
            if (m.lookingAt())
            {
                int power = Integer.parseInt(m.group(1));
                v = Math.scalb(v, power);

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