apache/dubbo · error · IllegalStateException

unsupported route engine type: {type}

Error message

unsupported route engine type: {type}

What it means

Thrown by ScriptStateRouter.getEngine() when ScriptEngineManager.getEngineByName(type) returns null — no JSR-223 script engine is registered under the configured name. The 'type' parameter defaults to a standard type (DEFAULT_SCRIPT_TYPE_KEY) but if the named engine is not on the classpath the router cannot function.

Source

Thrown at dubbo-cluster/src/main/java/org/apache/dubbo/rpc/cluster/router/script/ScriptStateRouter.java:129

     */
    private String getRule(URL url) {
        String vRule = url.getParameterAndDecoded(RULE_KEY);
        if (StringUtils.isEmpty(vRule)) {
            throw new IllegalStateException("route rule can not be empty.");
        }
        return vRule;
    }

    /**
     * create ScriptEngine instance by type from url parameters, then cache it
     */
    private ScriptEngine getEngine(URL url) {
        String type = url.getParameter(TYPE_KEY, DEFAULT_SCRIPT_TYPE_KEY);

        return ConcurrentHashMapUtils.computeIfAbsent(ENGINES, type, t -> {
            ScriptEngine scriptEngine = new ScriptEngineManager().getEngineByName(type);
            if (scriptEngine == null) {
                throw new IllegalStateException("unsupported route engine type: " + type);
            }
            return scriptEngine;
        });
    }

    @Override
    protected BitList<Invoker<T>> doRoute(
            BitList<Invoker<T>> invokers,
            URL url,
            Invocation invocation,
            boolean needToPrintMessage,
            Holder<RouterSnapshotNode<T>> nodeHolder,
            Holder<String> messageHolder)
            throws RpcException {
        if (engine == null || function == null) {
            if (needToPrintMessage) {
                messageHolder.set("Directly Return. Reason: engine or function is null");
            }

View on GitHub (pinned to 3a3043227f)

Solutions

1. Add a JSR-223 engine implementation to the classpath: for JavaScript on Java 15+ add the standalone Nashorn (org.openjdk.nashorn:nashorn-core) or GraalJS (org.graalvm.js:js-scriptengine + js); for Groovy add groovy-jsr223.
2. Use an engine name that the registered engine actually publishes (try 'nashorn', 'js', 'graal.js', or 'groovy' depending on the jar).
3. If no engine is desired, switch the router to a different type (condition/script-free) or remove it.

Example fix

# before (broken, Java 15+): nashorn removed -> getEngineByName returns null
script://0.0.0.0/...?type=javascript&rule=...

# after: add graaljs to pom and use its engine name
# pom: org.graalvm.js:js-scriptengine, org.graalvm.js:js, org.graalvm.regex
script://0.0.0.0/...?type=graal.js&rule=...
# (or add org.openjdk.nashorn:nashorn-core and keep type=javascript)

// Validate the script engine is available before constructing the router
String type = url.getParameter(TYPE_KEY, DEFAULT_SCRIPT_TYPE_KEY);
ScriptEngine engine = new ScriptEngineManager().getEngineByName(type);
if (engine == null) {
    throw new IllegalArgumentException(
        "No JSR-223 script engine named '" + type + "' on classpath. "
            + "Add nashorn-core (Java 15+) or graaljs/groovy-jsr223.");
}
return new ScriptStateRouter<>(url);

// Guard: an engine for the requested type exists
static boolean engineAvailable(String type) {
    return new ScriptEngineManager().getEngineByName(type) != null;
}

try {
    new ScriptStateRouter<>(url);
} catch (IllegalStateException e) {
    if (e.getMessage().contains("unsupported route engine type")) {
        // engine jar missing; log and fall back to a non-script router
        log.error("Script router engine missing: " + e.getMessage()
            + " Add org.openjdk.nashorn:nashorn-core or graaljs.");
    } else throw e;
}

When it happens

Trigger: Configuring a script router with type=<name> for which no javax.script engine is available. Most common: using type=javascript on Java 15+, where Nashorn was removed and getEngineByName('javascript'/'js') returns null.

Common situations: Running on Java 15+ (Nashorn removed) and using javascript script routing; specifying an engine name that does not match any registered engine (e.g., 'groovy' without the groovy-jsr223 dependency); missing the JSR-223 implementation jar on the classpath.

Related errors

• route rule can not be empty.
• INTERNAL_ERROR
• Illegal affinity rule!
• Illegal route rule!
• Illegal route rule!

AI-assisted analysis of apache/dubbo@3a3043227f (2026-08-14). Data as JSON: /api/errors/7ce82a200637e93b. Report an issue: GitHub.