flowable/flowable-engine · error · FlowableIllegalArgumentException

taskId and taskIds are null

Error message

taskId and taskIds are null

What it means

FlowableIllegalArgumentException thrown by DeleteTaskCmd.execute when neither taskId nor taskIds was supplied. The command needs at least one task identifier to know which task(s) to delete. It is a null/empty argument guard at the start of execution.

Source

Thrown at modules/flowable-cmmn-engine/src/main/java/org/flowable/cmmn/engine/impl/cmd/DeleteTaskCmd.java:58

        this.deleteReason = deleteReason;
    }

    public DeleteTaskCmd(Collection<String> taskIds, String deleteReason, boolean cascade) {
        this.taskIds = taskIds;
        this.cascade = cascade;
        this.deleteReason = deleteReason;
    }

    @Override
    public Void execute(CommandContext commandContext) {
        if (taskId != null) {
            deleteTask(commandContext, taskId);
        } else if (taskIds != null) {
            for (String taskId : taskIds) {
                deleteTask(commandContext, taskId);
            }
        } else {
            throw new FlowableIllegalArgumentException("taskId and taskIds are null");
        }

        return null;
    }

    protected void deleteTask(CommandContext commandContext, String taskId) {
        CmmnEngineConfiguration cmmnEngineConfiguration = CommandContextUtil.getCmmnEngineConfiguration(commandContext);
        TaskHelper.deleteTask(taskId, deleteReason, cascade, cmmnEngineConfiguration);
    }
}

View on GitHub (pinned to d6d39ce1c6)

Solutions

1. Check taskId != null || (taskIds != null && !taskIds.isEmpty()) before calling deleteTask
2. Populate taskIds from a validated source and fail early in the caller
3. If no ids is a legitimate case, skip the call rather than invoking it

Example fix

// before
taskService.deleteTask(taskId, taskIds);
// after
if (taskId != null) {
    taskService.deleteTask(taskId);
} else if (taskIds != null && !taskIds.isEmpty()) {
    for (String id : taskIds) taskService.deleteTask(id);
}

if (taskId == null && (taskIds == null || taskIds.isEmpty())) throw new IllegalArgumentException("taskId or taskIds required");

boolean hasTarget = taskId != null || (taskIds != null && !taskIds.isEmpty());

When it happens

Trigger: Calling taskService.deleteTask(null) or a batch delete API where both the single taskId and the taskIds collection are null/empty.

Common situations: Batch job where the id list came from an empty DB query; optional taskId variable never set; passing an empty List instead of null and neither field was populated.

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

• taskId is null
• Must specify a case instance id to migrate
• Must specify a case instance migration document to migrate
• Must specify a case definition id to migrate
• Null task id

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/fdba89943e53bf41. Report an issue: GitHub.