apache/dolphinscheduler · error · RuntimeException

mapreduce task params is not valid

Error message

mapreduce task params is not valid

What it means

A parameter validation guard in MapReduceTask.init: mapreduceParameters is null after parsing taskParams (invalid JSON) or checkParameters() failed because required fields (main jar, main class, program arguments as applicable) are missing. The offending input is the taskParams JSON in the task definition; the task fails before the hadoop command is built.

Source

Thrown at dolphinscheduler-task-plugin/dolphinscheduler-task-mr/src/main/java/org/apache/dolphinscheduler/plugin/task/mr/MapReduceTask.java:61

    private MapReduceParameters mapreduceParameters;

    private final TaskExecutionContext taskExecutionContext;

    public MapReduceTask(TaskExecutionContext taskExecutionContext) {
        super(taskExecutionContext);
        this.taskExecutionContext = taskExecutionContext;
    }

    @Override
    public void init() {

        this.mapreduceParameters =
                JSONUtils.parseObject(taskExecutionContext.getTaskParams(), MapReduceParameters.class);

        // check parameters
        if (mapreduceParameters == null || !mapreduceParameters.checkParameters()) {
            throw new RuntimeException("mapreduce task params is not valid");
        }

        // replace placeholder,and combine local and global parameters
        Map<String, Property> paramsMap = taskExecutionContext.getPrepareParamsMap();

        String args = ParameterUtils.convertParameterPlaceholders(mapreduceParameters.getMainArgs(),
                ParameterUtils.convert(paramsMap));
        mapreduceParameters.setMainArgs(args);
        if (mapreduceParameters.getProgramType() != null
                && mapreduceParameters.getProgramType() == ProgramType.PYTHON) {
            String others = ParameterUtils.convertParameterPlaceholders(mapreduceParameters.getOthers(),
                    ParameterUtils.convert(paramsMap));
            mapreduceParameters.setOthers(others);
        }
        log.info("Initialize mapreduce task params {}", JSONUtils.toPrettyJsonString(mapreduceParameters));
    }

    /**

View on GitHub (pinned to 02eac45a1b)

Solutions

1. Complete the required MapReduce fields (mainJar, mainClass) in the task definition
2. Ensure taskParams JSON deserializes into MapReduceParameters — check field names/types
3. Validate on save in the UI to surface missing fields before execution

When it happens

Trigger: Thrown at dolphinscheduler-task-plugin/dolphinscheduler-task-mr/src/main/java/org/apache/dolphinscheduler/plugin/task/mr/MapReduceTask.java:61 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/dolphinscheduler@02eac45a1b (2026-09-06). Data as JSON: /api/errors/294bd3d5dea0c2cb. Report an issue: GitHub.