**Apache Airflow version:**

2.0.0

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

1.18.3

**Environment:**

Cloud provider or hardware configuration: AWS

**What happened:**

When trying to run a DAG, it gets scheduled, but task is never run. When attempting to run task manually, it shows an error:

```
Something bad has happened.
Please consider letting us know by creating a bug report using GitHub.

Python version: 3.8.7
Airflow version: 2.0.0
Node: airflow-web-ffdd89d6-h98vj
-------------------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.8/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.8/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/local/lib/python3.8/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/usr/local/lib/python3.8/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.8/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/local/lib/python3.8/site-packages/airflow/www/auth.py", line 34, in decorated
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/airflow/www/decorators.py", line 60, in wrapper
    return f(*args, **kwargs)
  File "/usr/local/lib/python3.8/site-packages/airflow/www/views.py", line 1366, in run
    executor.start()
  File "/usr/local/lib/python3.8/site-packages/airflow/executors/kubernetes_executor.py", line 493, in start
    raise AirflowException("Could not get scheduler_job_id")
airflow.exceptions.AirflowException: Could not get scheduler_job_id
```

**What you expected to happen:**

The task to be run successfully without 

**How to reproduce it:**

Haven't pinpointed what causes the issue, besides an attempted upgrade from Airflow 1.10.14 to Airflow 2.0.0

**Anything else we need to know:**

This error is encountered in an upgrade of Airflow from 1.10.14 to Airflow 2.0.0

EDIT: Formatted to fit the issue template
airflow/cli/commands/task_command.py
if args.post_mortem:
            debugger = _guess_debugger()
            debugger.post_mortem()
        else:
            raise
    finally:
        if not already_has_stream_handler:
            
            
            logging.getLogger('airflow.task').propagate = False
@cli_utils.action_logging
@suppress_logs_and_warning
def task_render(args):
    """Renders and displays templated fields for a given task"""
    dag = get_dag(args.subdir, args.dag_id)
    task = dag.get_task(task_id=args.task_id)
    ti = TaskInstance(task, args.execution_date)
    ti.render_templates()
    for attr in task.__class__.template_fields:
        print(
            textwrap.dedent(
                f"""        # ----------------------------------------------------------
        # property: {attr}
        # ----------------------------------------------------------
        {getattr(task, attr)}
        """
            )
        )
@cli_utils.action_logging
def task_clear(args):