jupyter_contrib_nbextensions/docs/source/troubleshooting.md

Troubleshooting

If you are migrating from an older version of the contrib notebook extensions repository, some old files might be left on your system. This can lead, for example, to having all the nbextensions listed twice on the configurator page.

The nbextensions from older versions will be located in the nbextensions subdirectory in one of the data directories that can be found using the jupyter --paths command. If you run your notebook server with the --debug flag, you should also be able to tell where the extra nbextensions are located from jupyter server logs produced by the jupyter_nbextensions_configurator serverextension.