flowable/flowable-engine · error · FlowableIllegalArgumentException

script is required

Error message

script is required

What it means

FlowableScriptEvaluationRequest.evaluate() re-validates the request before executing: if the script field was never set (null or empty) it throws FlowableIllegalArgumentException('script is required'). This is the evaluate-time counterpart of the builder-time 'script is empty' check.

Solutions

1. Always call script(<code>) with non-empty script text before evaluate().
2. Validate the script source (variable, file, template) before constructing the request.
3. Fail early with a domain-specific message when the script source is blank.

Example fix

// before
var req = new FlowableScriptEvaluationRequest().language("groovy");
req.evaluate();

// after
var req = new FlowableScriptEvaluationRequest()
    .language("groovy")
    .script("return x * 2");
req.evaluate();

if (script == null || script.trim().isEmpty()) {
    throw new IllegalStateException("Cannot evaluate script: script was never set on the request");
}

boolean isEvaluableRequest(FlowableScriptEvaluationRequest r) { return r != null && r.getScript() != null && !r.getScript().isEmpty(); }

try {
    return request.evaluate();
} catch (FlowableIllegalArgumentException e) {
    throw new IllegalStateException("Script request incomplete: " + e.getMessage(), e);
}

When it happens

Trigger: Building a FlowableScriptEvaluationRequest without calling script(...) and invoking evaluate(); or the script text was set from a source that returned null/empty after the builder check path was bypassed.

Common situations: Programmatic script evaluation with conditionally omitted script body; process variables/expressions expected to supply the script content but resolving to empty.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

• A script is required
• language is required
• A resource name is mandatory
• An event definition key is mandatory
• language is empty

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/2a78d9c7156d7e0b. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-engine-common/src/main/java/org/flowable/common/engine/impl/scripting/JSR223FlowableScriptEngine.java:194

        public FlowableScriptEvaluationRequest inputVariableContainer(VariableContainer inputVariableContainer) {
            this.inputVariableContainer = inputVariableContainer;
            return this;
        }

        @Override
        public FlowableScriptEvaluationRequest storeScriptVariables() {
            this.storeScriptVariables = true;
            return this;
        }

        @Override
        public ScriptEvaluation evaluate() throws FlowableScriptException {
            if (StringUtils.isEmpty(language)) {
                throw new FlowableIllegalArgumentException("language is required");
            }

            if (StringUtils.isEmpty(script)) {
                throw new FlowableIllegalArgumentException("script is required");
            }

            ScriptEngine scriptEngine = getEngineByName(language);
            Bindings bindings = createBindings();
            try {
                Object result = scriptEngine.eval(script, bindings);
                return new ScriptEvaluationImpl(resolver, result);
            } catch (ScriptException e) {
                throw new FlowableScriptException(e.getMessage(), e);
            }
        }

        protected Bindings createBindings() {
            return new ScriptBindings(Collections.singletonList(resolver), scopeContainer, inputVariableContainer, storeScriptVariables);
        }
    }
}

View on GitHub (pinned to d6d39ce1c6)