configuration error when initializing jupyter lab

Following is the information of error when initializing Jupyter lab. The error seems not serious, but I cannot open the webpage. How do I fix it? To my surprise, Jupyter notebook works well.

[~] jupyter lab

[I ... ServerApp] jupyterlab | extension was successfully linked. [W 2021-08-28 11:32:26.627 NotebookApp] 'browser' has moved from NotebookApp to ServerApp. This config will be passed to ServerApp. Be sure to update your config before our next release.

[W ... NotebookApp] 'notebook_dir' has moved from NotebookApp to ServerApp. This config will be passed to ServerApp. Be sure to update your config before our next release.

[C ... NotebookApp] Bad config encountered during initialization: Trait, server_extensions, not found.

Thanks for the helps. All errors are vanished, except the last info: Bad config encountered during initialization: Trait, server_extensions, not found.

There is a json file in configuration dir, it writes

{
  "NotebookApp": {
    "server_extensions": [
      "jupyter_nbextensions_configurator"
    ],
    "nbserver_extensions": {
      "jupyterlab": true
    }
  }
}

Finally, I reinstall jupyterlab after delete the config dir. It just works now. I should end the topic.