To migrate from notebook server to plain jupyter server, follow these steps:
Rename your jupyter_notebook_config.py file to jupyter_server_config.py.
Rename all c.NotebookApp traits to c.ServerApp.
For example if you have the following jupyter_notebook_config.py.
c.NotebookApp.allow_credentials = False
c.NotebookApp.port = 8889
c.NotebookApp.password_required = True
You will have to create the following jupyter_server_config.py file.
c.ServerApp.allow_credentials = False
c.ServerApp.port = 8889
c.ServerApp.password_required = True
If you want to switch to Jupyter Server, but you still want to serve Jupyter Notebook to users, you can try NBClassic.
NBClassic is a Jupyter Server extension that serves the Notebook frontend (i.e. all static assets) on top of Jupyter Server. It even loads Jupyter Notebook’s config files.
NBClassic will only work for a limited time. Jupyter Server is likely to evolve beyond a point where Jupyter Notebook frontend will no longer work with the underlying server. Consider switching to JupyterLab or nteract where there is active development happening.