If you are running a JupyterHub on Kubernetes and use NFS for home directory storage (a common occurance), I highly recommend the following settings:

    # notebook server writes secure files that don't need to survive a
    # restart here. Writing 'secure' files on some file systems (like
    # Azure Files with SMB or NFS) seems buggy, so we just put runtime dir on
    # /tmp. This is ok in our case, since no two users are on the same
    # container.
    JUPYTER_RUNTIME_DIR: /tmp/.jupyter-runtime
      mountPath: /usr/local/etc/ipython/ipython_kernel_config.json
        # This keeps a history of all executed code under $HOME, which is almost always on
        # NFS. This file is kept as a sqlite file, and sqlite and NFS do not go together very
        # well! Disable this to save ourselves from debugging random NFS oddities that are caused
        # by this unholy sqlite + NFS mixture.
          enabled: false

These aren’t specific to kubernetes, but to NFS (or AzureFile, or any other shared filesystem). sqlite and NFS do not mix, and you’ll run into weird errors you will not be able to really debug. Save yourself the pain :) Let your users know too, and tell them to not put sqlite databases on NFS.