To help collaborators avoid overwriting each other's work in a notebook, Terra locks a notebook when it is in use by another user. The first user can choose to run a notebook in Edit mode. Subsequent users will only be able to run in Playground mode where they can execute code in the notebook but cannot save changes back to the workspace. To learn more about these two notebook editing modes, see this article on "Edit" and "Playground" modes.
To accommodate the two modes, the directory where notebooks and notebook data are stored on the virtual machine vary depending on whether you are in "edit" or "playground" mode.
All data files and subfolders are located in /home/jupyter/ (or /home/jupyter-user/ for older notebooks). From there, you can navigate into the workspace directory where you will see the edit and safe directories. These two directories contain the data generated in "edit" and "playground" modes, respectively.
Note that previously, these files were located in home/jupyter-user/notebooks/ and file paths inside your notebooks pointing to local data files may need to be updated accordingly.
Example
If a datafile previously lived in the notebooks directory it looked like this:
/home/jupyter-user/notebooks/datafile.txt
With the new changes to the directory structure it becomes:
/home/jupyter/datafile.txt