Read more details about the changes currently taking place in the Jupyter Ecosystem in the JEP 79 and team-compass note.
Notebook 7 is built on top of JupyterLab components and delivers new features like realtime collaboration, debugger, theming.
Any extension developed for Notebook < 7 or NbClassic will not be compatible with Notebook 7 and upwards.
Some extensions like nbgrader have already been ported. We invite you to check if the extensions you are using have already been ported.
NbClassic and Notebook 7
You can install NbClassic, Notebook 7 and JupyterLab, all three of which will provide different user interfaces on the same server. When Notebook 7 is available, the NbClassic UI, will be served at the /nbclassic/tree base path rather than the base path /tree used otherwise. If you are using Notebook 7 along with NbClassic, you will also have JupyterLab installed as it is a dependency of Notebook 7, and these front ends will be available through the following base paths: JupyterLab at /lab, Notebook 7 at /tree, and NbClassic at /nbclassic/tree.
NbClassic and Notebook 6.5.x
As NbClassic provides the static assets for Notebook 6.5.x, while having both installed should cause no issues, the user interface provided by these two packages will be the same. These UIs will be served by different back end servers. An NbClassic instance will be at a server with the /tree path and opening a Notebook 6.5.x instance will open on a different server with the /tree path as well, presenting the same static assets. When starting an instance of JupyterLab you will be able to access the classic view of Notebook with NbClassic served on the same server at /tree.
NbClassic and Notebook <= 6.4.x
When using NbClassic and Notebook <= 6.4.x you can expect that these UIs will not be only presented at different servers, meaning they will both be available at their respective server under /tree but they may also differ as potential changes to the NbClassic UI will not be reflected in Notebook versions <= 6.4.x. In this case as well, you would be able to access the classic view of Notebook with NbClassic served on the same server, at /tree.
NbClassic and JupyterLab 3.x
When only JupyterLab 3.x is installed, then NbClassic does not have to be explicitly installed as JupyterLab 3.x depends on it. They will run on the same server, and are reachable via /tree for NbClassic and /lab for JupyterLab.
NbClassic and JupyterLab 4.x
When only JupyterLab 4.x is installed, then NbClassic has to be installed explictly. They will run on the same server, and are reachable via /tree for NbClassic, and /lab for JupyterLab.
NbClassic Independently
When you choose to install only NbClassic via pip install nbclassic, the classic Notebook UI will be presented at the /tree path. As the other frontends are not installed, attempting to access the other paths will return errors. Note that NbClassic being a Jupyter Server extension, indicated Jupyter Server will be available. This provides an additional way to view the NbClassic frontend. You would be able to manually enable the extension when running an instance of Jupyter Server, > jupyter server --ServerApp.jpserver_extensions="nbclassic=True", which will provide the NbClassic frontend at /tree path when visited.