apache/dolphinscheduler · error · TaskException

cancel paragraph error

Error message

cancel paragraph error

What it means

ZeppelinTask.cancelApplication wraps any exception from zClient.cancelParagraph(noteId, paragraphId) into a TaskException with the message 'cancel paragraph error'. It means the attempt to terminate a running Zeppelin paragraph via the Zeppelin client API failed. The underlying cause (network problem, invalid note/paragraph id, Zeppelin server down) is attached as the cause.

Source

Thrown at dolphinscheduler-task-plugin/dolphinscheduler-task-zeppelin/src/main/java/org/apache/dolphinscheduler/plugin/task/zeppelin/ZeppelinTask.java:246

    @Override
    public void cancelApplication() throws TaskException {
        final String restEndpoint = this.zeppelinParameters.getRestEndpoint();
        final String noteId = this.zeppelinParameters.getNoteId();
        final String paragraphId = this.zeppelinParameters.getParagraphId();
        if (paragraphId == null) {
            log.info("trying terminate zeppelin task, taskId: {}, noteId: {}",
                    this.taskExecutionContext.getTaskInstanceId(), noteId);
            Unirest.config().defaultBaseUrl(restEndpoint + "/api");
            Unirest.delete("/notebook/job/{noteId}").routeParam("noteId", noteId).asJson();
            log.info("zeppelin task terminated, taskId: {}, noteId: {}", this.taskExecutionContext.getTaskInstanceId(),
                    noteId);
        } else {
            log.info("trying terminate zeppelin task, taskId: {}, noteId: {}, paragraphId: {}",
                    this.taskExecutionContext.getTaskInstanceId(), noteId, paragraphId);
            try {
                this.zClient.cancelParagraph(noteId, paragraphId);
            } catch (Exception e) {
                throw new TaskException("cancel paragraph error", e);
            }
            log.info("zeppelin task terminated, taskId: {}, noteId: {}, paragraphId: {}",
                    this.taskExecutionContext.getTaskInstanceId(), noteId, paragraphId);
        }

    }

    @Override
    public List<String> getApplicationIds() throws TaskException {
        return Collections.emptyList();
    }

    public void addDefaultOutput(String response) {
        // put response in output
        Property outputProperty = new Property();
        outputProperty.setProp(String.format("%s.%s", taskExecutionContext.getTaskName(), "result"));
        outputProperty.setDirect(Direct.OUT);
        outputProperty.setType(DataType.VARCHAR);

View on GitHub (pinned to 02eac45a1b)

Solutions

  1. Verify the Zeppelin server URL and credentials in the task/plugin configuration are correct and the server is reachable (curl the REST endpoint).
  2. Check the wrapped cause in the TaskException stack trace for the real Zeppelin client error.
  3. Confirm noteId and paragraphId were captured from the task output correctly; re-run the task to get fresh IDs if the paragraph already finished.
  4. Retry the cancel; if the paragraph already completed, treat the task as finished instead of failed.

Example fix

// before
try {
    this.zClient.cancelParagraph(noteId, paragraphId);
} catch (Exception e) {
    throw new TaskException("cancel paragraph error", e);
}
// after
try {
    this.zClient.cancelParagraph(noteId, paragraphId);
} catch (Exception e) {
    log.warn("Cancel paragraph failed, noteId: {}, paragraphId: {}", noteId, paragraphId, e);
    throw new TaskException("cancel paragraph error, noteId: " + noteId + ", paragraphId: " + paragraphId, e);
}
Defensive patterns

Strategy: try-catch

Validate before calling

// before cancelling, verify the paragraph is still running
String status = zeppelinClient.getParagraphStatus(noteId, paragraphId);
if (!"RUNNING".equals(status)) { log.info("paragraph {} already finished", paragraphId); return; }
// and verify the server is reachable
// new java.net.URL(zeppelinUrl).openConnection().connect();

Try / catch

try {
    task.cancel();
} catch (TaskException e) {
    log.error("Zeppelin cancel failed: {}", e.getCause() != null ? e.getCause().getMessage() : e.getMessage(), e);
    // decide whether to rethrow based on whether the task is still running
}

Prevention

When it happens

Trigger: Calling cancelApplication (task kill/cancel from DolphinScheduler) when the Zeppelin client throws while cancelling the paragraph: Zeppelin server unreachable, noteId/paragraphId invalid or already finished, or an authentication/session error in ZeppelinClient.

Common situations: Killing a running Zeppelin task whose Zeppelin server has been restarted or is down; stale paragraphId from a prior run; Zeppelin returning an error for an already-completed paragraph; network/firewall issues between the worker and Zeppelin.

Understand the failure class

Background: "API request failed": what wrapped HTTP errors from external APIs mean and how to find the real cause — this error's family across 29 libraries.

Related errors

AI-assisted analysis of apache/dolphinscheduler@02eac45a1b (2026-09-06). Data as JSON: /api/errors/5ac21823c25f2bba. Report an issue: GitHub.