Airflow -D not working, not running in the background - airflow

Question

I can start webserver normally, with the command airflow webserver. but when I use airflow webserver -D, it shows:
/data/software/miniconda3/lib/python3.7/site-packages/airflow/config_templates/airflow_local_settings.py:65: DeprecationWarning: The elasticsearch_host option in [elasticsearch] has been renamed to host - the old setting has been used, but please update your config.
ELASTICSEARCH_HOST = conf.get('elasticsearch', 'HOST')
/data/software/miniconda3/lib/python3.7/site-packages/airflow/config_templates/airflow_local_settings.py:67: DeprecationWarning: The elasticsearch_log_id_template option in [elasticsearch] has been renamed to log_id_template - the old setting has been used, but please update your config.
ELASTICSEARCH_LOG_ID_TEMPLATE = conf.get('elasticsearch', 'LOG_ID_TEMPLATE')
/data/software/miniconda3/lib/python3.7/site-packages/airflow/config_templates/airflow_local_settings.py:69: DeprecationWarning: The elasticsearch_end_of_log_mark option in [elasticsearch] has been renamed to end_of_log_mark - the old setting has been used, but please update your config.
ELASTICSEARCH_END_OF_LOG_MARK = conf.get('elasticsearch', 'END_OF_LOG_MARK')
[2019-12-25 06:37:49,537] {settings.py:252} INFO - settings.configure_orm(): Using pool settings. pool_size=5, max_overflow=10, pool_recycle=1800, pid=855
____________ _____________
____ |__( )_________ __/__ /________ __
____ /| |_ /__ ___/_ /_ __ /_ __ \_ | /| / /
___ ___ | / _ / _ __/ _ / / /_/ /_ |/ |/ /
_/_/ |_/_/ /_/ /_/ /_/ \____/____/|__/
[2019-12-25 06:37:50,031] {__init__.py:51} INFO - Using executor LocalExecutor
[2019-12-25 06:37:50,031] {dagbag.py:92} INFO - Filling up the DagBag from /data/projects/airflow/dags
Running the Gunicorn Server with:
Workers: 4 sync
Host: 0.0.0.0:8080
Timeout: 120
Logfiles: - -
=================================================================
Then, there is not any process running in the background later. I check with the commandps -ef|grep airflow.
The version of Airflow is 1.10.6.
In previous versions, -D used to work fine

Answer 1

If you can run airflow webserver normally. No errors for airflow webserver -D, and you can not find the process running as airflow webserver.
It must be you killed the background process of airflow webserver -D, and you didn't delete the pid file of airflow webserver.
You can go to the $AIRFLOW_HOME/airflow directory, check the pid files. If exists and not empty, delete it and retry:
cd $AIRFLOW_HOME/airflow
rm airflow-webserver*.pid
airflow webserver -D