locustio/locust · error · Exception

User.run() is a method used internally by Locust, and you mu

Error message

User.run() is a method used internally by Locust, and you must not override it or register it as a task

What it means

Locust's User.run() method drives the internal task-execution loop. Registering a method named `run` as a task via @task would shadow it, so the @task decorator raises immediately to prevent this.

Source

Thrown at locust/user/task.py:84

            @task(25)
            class ForumThread(TaskSet):
                @task
                def get_author(self):
                    pass

                @task
                def get_created(self):
                    pass
    """

    def decorator_func(func):
        if func.__name__ in ["on_stop", "on_start"]:
            logging.warning(
                "You have tagged your on_stop/start function with @task. This will make the method get called both as a task AND on stop/start."
            )  # this is usually not what the user intended
        if func.__name__ == "run":
            raise Exception(
                "User.run() is a method used internally by Locust, and you must not override it or register it as a task"
            )
        func.locust_task_weight = weight
        return func

    """
    Check if task was used without parentheses (not called), like this::

        @task
        def my_task(self)
            pass
    """
    if callable(weight):
        func = weight
        weight = 1
        return decorator_func(func)
    else:
        return decorator_func

View on GitHub (pinned to f391a716e1)

Solutions

1. Rename the method to something other than `run`
2. Move custom loop logic into a normal @task method or on_start
3. If overriding run intentionally, subclass and override without @task (rarely needed)

Example fix

// before
class MyUser(User):
    @task
    def run(self):
        ...
// after
class MyUser(User):
    @task
    def run_scenario(self):
        ...

assert not any(getattr(m, '__name__', '') == 'run' for m in vars(MyUser).values() if callable(m)), "Do not decorate run() with @task"

When it happens

Trigger: Applying @task (or @task(weight)) to a method named `run` on a User or TaskSet class.

Common situations: Users subclassing User and adding their own `run` logic, or renaming an existing task to `run`, then decorating it.

Related errors

• In order to use a with-block for requests, you must also pas
• Tried to set status on a request that has not yet been made.
• use start_worker
• No tag name was supplied
• No tasks defined on {self.__class__.__name__}{extra_message}

AI-assisted analysis of locustio/locust@f391a716e1 (2026-08-29). Data as JSON: /api/errors/f1a6083146943bb8. Report an issue: GitHub.