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**Apache Airflow version**: 932f8c2e9360de6371031d4d71df00867a2776e6


**Kubernetes version (if you are using kubernetes)** (use `kubectl version`):

**Environment**: locally run `airflow server`

- **Cloud provider or hardware configuration**:
- **OS** (e.g. from /etc/os-release): mac
- **Kernel** (e.g. `uname -a`):
- **Install tools**:
- **Others**:

**What happened**:

<!-- (please include exact error messages if you can) -->

Task doc is shown on Airflow v1 Task Instance Detail view but not shown on v2.

**What you expected to happen**:

<!-- What do you think went wrong? -->

Task doc is shown.

**How to reproduce it**:

- install airflow latest master
- `airflow server`
- open `tutorial_etl_dag` in `example_dags`
- run dag(I don't know why but task instance detail can't open with error if no dag runs) and open task instance detail

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As minimally and precisely as possible. Keep in mind we do not have access to your cluster or dags.

If you are using kubernetes, please attempt to recreate the issue using minikube or kind.

## Install minikube/kind

- Minikube https://minikube.sigs.k8s.io/docs/start/
- Kind https://kind.sigs.k8s.io/docs/user/quick-start/

If this is a UI bug, please provide a screenshot of the bug or a link to a youtube video of the bug in action

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airflow/www/views.py
"""Mark task as failed."""
        dag_id = request.form.get('dag_id')
        task_id = request.form.get('task_id')
        origin = get_safe_url(request.form.get('origin'))
        execution_date = request.form.get('execution_date')
        confirmed = request.form.get('confirmed') == "true"
        upstream = request.form.get('failed_upstream') == "true"
        downstream = request.form.get('failed_downstream') == "true"
        future = request.form.get('failed_future') == "true"
        past = request.form.get('failed_past') == "true"
        return self._mark_task_instance_state(
            dag_id,
            task_id,
            origin,