flowable/flowable-engine · error · FlowableObjectNotFoundException

Task '' does not have a comment with id ''.

Error message

Task '' does not have a comment with id ''.

What it means

Reading a task comment via GET /runtime/tasks/{taskId}/comments/{commentId} throws FlowableObjectNotFoundException when the comment id does not exist or exists but belongs to a different task. The comment is looked up by id and its taskId must match the requested task.

Solutions

1. Verify the commentId exists via GET /runtime/tasks/{taskId}/comments and use one from the list
2. Confirm the comment belongs to the same taskId in the URL path
3. Re-fetch the comment list if the comment was recently deleted

const comments = await get(`/runtime/tasks/${taskId}/comments`);
if (!comments.some(c => c.id === commentId)) return null;

try { ... } catch (e) { if (e.status === 404) return null; throw e; }

When it happens

Trigger: GET /runtime/tasks/{taskId}/comments/{commentId} where commentId is unknown, already deleted, or attached to another task's id.

Common situations: Stale ids cached by a client after comment deletion; copying a comment id from another task; historic-task endpoint used with a comment on the runtime task of a different id.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Could not find a app model json with id
• Could not find a deployment with id
• Could not find a milestone instance with id
• Could not find a plan item instance with id
• Could not find a resource with id

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/a1f34f26ac00b3ba. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-rest/src/main/java/org/flowable/rest/service/api/runtime/task/TaskCommentResource.java:54

 * @author Frederik Heremans
 */
@RestController
@Api(tags = { "Task Comments" }, authorizations = { @Authorization(value = "basicAuth") })
public class TaskCommentResource extends TaskBaseResource {

    @ApiOperation(value = " Get a comment on a task", tags = { "Task Comments" }, nickname = "getTaskComment")
    @ApiResponses(value = {
            @ApiResponse(code = 200, message = "Indicates the task and comment were found and the comment is returned."),
            @ApiResponse(code = 404, message = "Indicates the requested task was not found or the tasks does not have a comment with the given ID.")
    })
    @GetMapping(value = "/runtime/tasks/{taskId}/comments/{commentId}", produces = "application/json")
    public CommentResponse getComment(@ApiParam(name = "taskId") @PathVariable("taskId") String taskId, @ApiParam(name = "commentId") @PathVariable("commentId") String commentId) {

        HistoricTaskInstance task = getHistoricTaskFromRequest(taskId);

        Comment comment = taskService.getComment(commentId);
        if (comment == null || !task.getId().equals(comment.getTaskId())) {
            throw new FlowableObjectNotFoundException("Task '" + task.getId() + "' does not have a comment with id '" + commentId + "'.", Comment.class);
        }

        return restResponseFactory.createRestComment(comment);
    }

    @ApiOperation(value = "Delete a comment on a task", tags = { "Task Comments" }, nickname = "deleteTaskComment", code = 204)
    @ApiResponses(value = {
            @ApiResponse(code = 204, message = "Indicates the task and comment were found and the comment is deleted. Response body is left empty intentionally."),
            @ApiResponse(code = 404, message = "Indicates the requested task was not found or the tasks does not have a comment with the given ID.")
    })
    @DeleteMapping(value = "/runtime/tasks/{taskId}/comments/{commentId}")
    @ResponseStatus(HttpStatus.NO_CONTENT)
    public void deleteComment(@ApiParam(name = "taskId") @PathVariable("taskId") String taskId, @ApiParam(name = "commentId") @PathVariable("commentId") String commentId) {

        // Check if task exists
        Task task = getTaskFromRequestWithoutAccessCheck(taskId);

        Comment comment = taskService.getComment(commentId);

View on GitHub (pinned to d6d39ce1c6)