conductor-oss/conductor · error · TerminateWorkflowException

Input has to be a JSON object: %s

Error message

Input has to be a JSON object: %s

What it means

Thrown by ValueParamEvaluator.evaluate() when the input object passed to the evaluator is not a Map. The value-param evaluator extracts a value by key from a JSON object (Map); it cannot operate on a scalar, list, or other type. This is used by SWITCH tasks with evaluatorType 'value-param'. A TerminateWorkflowException means the workflow is terminated with this error — it does not retry.

Source

Thrown at core/src/main/java/com/netflix/conductor/core/execution/evaluators/ValueParamEvaluator.java:40

@Component(ValueParamEvaluator.NAME)
public class ValueParamEvaluator implements Evaluator {

    public static final String NAME = "value-param";
    private static final Logger LOGGER = LoggerFactory.getLogger(ValueParamEvaluator.class);

    @SuppressWarnings("unchecked")
    @Override
    public Object evaluate(String expression, Object input) {
        LOGGER.debug("ValueParam evaluator -- evaluating: {}", expression);
        if (input instanceof Map) {
            Object result = ((Map<String, Object>) input).get(expression);
            LOGGER.debug("ValueParam evaluator -- result: {}", result);
            return result;
        } else {
            String errorMsg = String.format("Input has to be a JSON object: %s", input.getClass());
            LOGGER.error(errorMsg);
            throw new TerminateWorkflowException(errorMsg);
        }
    }
}

View on GitHub (pinned to cf7c3e4a8a)

Solutions

1. Inspect the SWITCH task's input parameters — ensure the value feeding the evaluator resolves to a JSON object (Map) at runtime.
2. Fix the upstream task so its output is a JSON object, not a scalar or array.
3. Change the evaluatorType to one that handles non-Map input, or restructure the input mapping.
4. Add a JSONata or Javascript expression upstream to coerce the value into an object before it reaches the SWITCH task.

Example fix

// workflow definition (before) — $.items is an array
{
  "type": "SWITCH",
  "evaluatorType": "value-param",
  "expression": "items",
  "inputParameters": { "items": "${workflow.output.items}" }
}

// after — extract a specific object key from the array
{
  "type": "SWITCH",
  "evaluatorType": "value-param",
  "expression": "status",
  "inputParameters": { "status": "${task1.output.status}" }
}

// Ensure SWITCH value-param input is a Map
Object inputForEval = taskInput.get(expression);
if (!(inputForEval instanceof Map)) {
    throw new IllegalStateException(
        "Expected JSON object for value-param, got: " + inputForEval.getClass());
}

private boolean isJsonMap(Object input) {
    return input instanceof Map;
}

When it happens

Trigger: A SWITCH task configured with evaluatorType 'value-param' where the expression resolves against task input that is a List, String, or null instead of a JSON object. The taskInput map provided to the evaluator is not a Map at runtime.

Common situations: A previous task outputs an array or scalar where the SWITCH task expects a JSON object. The input parameter mapping in the workflow definition produces a non-Map value due to a malformed ${...} expression. A JSON field that is expected to be an object is actually a string in the runtime data.

Related errors

• No evaluator registered for type: %s
• Tasks could not be dynamically forked due to invalid input:
• Input to the dynamically forked tasks is not a map -> expect
• Empty 'evaluatorType' in INLINE task's input parameters. A n
• Unknown evaluator '%s' in INLINE task.

AI-assisted analysis of conductor-oss/conductor@cf7c3e4a8a (2026-08-14). Data as JSON: /api/errors/ba0858ee71be9737. Report an issue: GitHub.