apache/cassandra · error · IllegalArgumentException

Unsupported object passed to resolve name_size: %s

Error message

Unsupported object passed to resolve name_size: %s

What it means

Thrown by UUIDRoleNameGenerator.getSize() when the resolved name_size object is neither a String nor a Number — i.e. an unsupported type such as Boolean, Map, or List. The message includes the class name of the offending object.

Source

Thrown at src/java/org/apache/cassandra/db/guardrails/UUIDRoleNameGenerator.java:182

        }

        int size;

        if (sizeObject instanceof String)
        {
            try
            {
                size = Integer.parseInt((String) sizeObject);
            }
            catch (Throwable t)
            {
                throw new IllegalArgumentException("Value '" + sizeObject + "' can't be converted to integer.");
            }
        }
        else if (sizeObject instanceof Number)
            size = ((Number) sizeObject).intValue();
        else
            throw new IllegalArgumentException("Unsupported object passed to resolve " + NAME_SIZE + ": " + sizeObject.getClass().getName());

        if (size < minimumNameSize)
            throw new IllegalArgumentException("Value of " + NAME_SIZE + " parameter has to be at least " + minimumNameSize + '.');

        if (size > MAXIMUM_NAME_SIZE)
            throw new IllegalArgumentException("Generator generates names of maximum length " + MAXIMUM_NAME_SIZE + ". " +
                                               "You want to generate with length " + size + '.');

        return size;
    }
}

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Ensure name_size is a String or Number before calling generate
2. Fix config so name_size is a scalar integer value, not a nested structure
3. Pre-validate with an instanceof (String || Number) check

Example fix

// before
options.put("name_size", Map.of("min", 8));
// after
options.put("name_size", "8");

Object v = options.get("name_size");
if (v != null && !(v instanceof String) && !(v instanceof Number))
    throw new IllegalArgumentException("name_size must be String or Number");

boolean isStringOrNumber(Object v) { return v instanceof String || v instanceof Number; }

try {
    generator.generate(options);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("Unsupported object passed to resolve name_size")) {
        // coerce the value to a String/Number and retry
    } else throw e;
}

When it happens

Trigger: Calling generate(options) with options.get("name_size") being any object that is not String or Number, e.g. a nested map from a misparsed config.

Common situations: Config layers deserializing 'name_size' into unexpected types (e.g. a YAML mapping instead of a scalar); programmatic misuse passing an enum or object wrapper.

Understand the failure class

Background: Type mismatch errors: IllegalArgumentException, TypeError and type guards across 150 open-source libraries — this error's family across 150 libraries.

Related errors

• Value of %s is not a string.
• Value of %s cannot be null.
• Value '%s' can't be converted to integer.
• Value of name_size has to be strictly positive integer.
• Value of name_size parameter has to be at least %s.

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/73e921e2dacb489e. Report an issue: GitHub.