apache/cassandra · error · ConfigurationException

%s must be a positive number, got %s

Error message

%s must be a positive number, got %s

What it means

ParameterizedFastPathStrategy.fromMap() parses the 'size' option from a string map of fast-path strategy options. If the value cannot be parsed as an integer (NumberFormatException), a ConfigurationException is thrown with this message. The 'positive number' wording means the value must be a valid positive integer.

Source

Thrown at src/java/org/apache/cassandra/service/accord/topology/ParameterizedFastPathStrategy.java:253

    private static ConfigurationException cfe(String fmt, Object... args)
    {
        return new ConfigurationException(String.format(fmt, args));
    }

    public static ParameterizedFastPathStrategy fromMap(Map<String, String> map)
    {
        if (!map.containsKey(SIZE))
            throw cfe("fast_path must be set to 'keyspace' or 'default' or a map defining '%s' and optionally '%s'", SIZE, DCS);

        int size;
        try
        {
            size = Integer.parseInt(map.get(SIZE));
        }
        catch (NumberFormatException e)
        {
            throw cfe("%s must be a positive number, got %s", SIZE, map.get(SIZE));
        }

        if (size < 1)
            throw cfe("%s must be greater than zero", SIZE);

        ImmutableMap<String, WeightedDc> dcMap;
        if (map.containsKey(DCS) && !map.get(DCS).isEmpty())
        {
            Map<String, WeightedDc> mutableDcs = new HashMap<>();
            String dcsString = map.get(DCS);
            if (dcsString.trim().isEmpty())
                throw cfe("%s must specify at least one DC", DCS);

            int autoIdx = 0;
            boolean hasAuto = false;
            boolean hasManual = false;
            for (String dcString : COMMA_SEPARATOR.split(dcsString))
            {

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Set the 'size' option to a plain positive integer string, e.g. {"size": "100"}
2. Remove unit suffixes or decimals ("10.5", "100ms") — only integers are accepted
3. Check for invisible whitespace or non-ASCII characters in the configured value

Example fix

// before
Map<String,String> opts = Map.of("size", "10.5");
ParameterizedFastPathStrategy.fromMap(opts); // throws
// after
Map<String,String> opts = Map.of("size", "10");
ParameterizedFastPathStrategy.fromMap(opts); // ok

String size = map.get("size");
if (size == null || !size.trim().matches("\\d+"))
    throw new IllegalArgumentException("size must be a positive integer, got: " + size);

When it happens

Trigger: Calling ParameterizedFastPathStrategy.fromMap() with a map whose 'size' entry is not parseable by Integer.parseInt, e.g. "size" -> "abc", "10.5", "", or "100ms".

Common situations: Typing a decimal or unit-suffixed value in cassandra.yaml / nodetool fast-path configuration; copy-pasting strategy options with stray whitespace or locale-formatted numbers.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Invalid accord progress log configuration:
• Concurrent accord operations must be non-negative
• DC weights must be zero or positive
• %s must be greater than zero
• %s must specify at least one DC

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/462c6fecb5a0fa7e. Report an issue: GitHub.