apache/cassandra · error · IllegalArgumentException

%s is not a valid function resource name

Error message

%s is not a valid function resource name

What it means

FunctionResource.fromName parses a stored function resource name such as 'functions', 'functions/<ks>' or 'functions/<ks>/<name>[args]'. It throws IllegalArgumentException when the first segment is not the literal root 'functions', meaning the string is not a valid function resource name.

Source

Thrown at src/java/org/apache/cassandra/auth/FunctionResource.java:192

     * Parses a resource name into a FunctionResource instance.
     * A valid resource name for function should be in the follow format:
     * functions/KEYSPACE/FUNCTION_NAME[FUNCTION_ARGS]
     * Note that
     * 1. FUNCTION_NAME could contain any character due to the use of quoted text in CQL.
     * 2. FUNCTION_ARGS could be empty. If it is not empty, it is expressed in this format:
     *    FUNCTION_ARG1^FUNCTION_ARG2... where ^ is the delimiter for arguments
     *
     * @param name Name of the function resource.
     * @return FunctionResource instance matching the name.
     */
    public static FunctionResource fromName(String name)
    {
        // Split the name into at most 3 parts.
        // The last part is the function name + args list, the name might contains '/'
        String[] parts = StringUtils.split(name, "/", 3);

        if (!parts[0].equals(ROOT_NAME))
            throw new IllegalArgumentException(String.format("%s is not a valid function resource name", name));

        if (parts.length == 1)
            return root();

        if (parts.length == 2)
            return keyspace(parts[1]);

        if (!name.matches("^.+\\[.*\\]$"))
            throw new IllegalArgumentException(String.format("%s is not a valid function resource name. It must end with \"[]\"", name));

        String function = parts[2];
        // The name must end with '[...]' block
        int lastStartingBracketIndex = function.lastIndexOf('[');
        String functionName = StringUtils.substring(function, 0, lastStartingBracketIndex);
        String functionArgs = StringUtils.substring(function,
                                                    // excludes the wrapping brackets [ ]
                                                    lastStartingBracketIndex + 1,
                                                    function.length() - 1);

View on GitHub (pinned to 88fd0f6a0e)

Solutions

1. Ensure the name begins with the exact root 'functions' followed by at most two more slash-separated segments
2. Use the typed factories FunctionResource.root()/keyspace()/function() instead of string parsing
3. Check that the resource kind matches: data resources must be parsed with DataResource.fromName, JMX with JMXResource.fromName

Example fix

// before
FunctionResource r = FunctionResource.fromName("data/ks/fn[int]");
// after
FunctionResource r = FunctionResource.fromName("functions/ks/fn[int]");

boolean isValidFunctionResourceName(String name) {
    String[] parts = name.split("/", 3);
    return parts.length >= 1 && "functions".equals(parts[0]);
}

try { FunctionResource r = FunctionResource.fromName(name); } catch (IllegalArgumentException e) { log.error("not a function resource: {}", name); }

When it happens

Trigger: Calling FunctionResource.fromName with a name whose first slash-segment is not 'functions' (e.g. 'data/ks/tbl', 'jmx/...', 'funtions/ks' typo), or with an empty string so parts[0] doesn't match.

Common situations: Mixing up resource-kind prefixes when deserializing permissions; corrupted or hand-edited entries in a permissions store; scripted grant statements that concatenate the wrong prefix.

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

• %s is not a valid data resource name
• %s is not a valid function resource name. It must end with "
• %s is not a valid JMX resource name
• REVOKE operation is not supported by AllowAllAuthorizer
• In this context function name must be explictly qualified by

AI-assisted analysis of apache/cassandra@88fd0f6a0e (2026-09-10). Data as JSON: /api/errors/971f96db341d2b11. Report an issue: GitHub.