What are some common mistakes that lead to the 'Runtime.ImportModuleError' when working with Jupyter Notebooks?

Jupyter Notebooks can sometimes have caching issues. 1) Restart the kernel: Kernel -> Restart. 2) Ensure the correct kernel is selected. 3) If you've modified 'index.py', you might need to reload the module using `importlib.reload(index)` after restarting the kernel. 4) Verify that the notebook is running in the correct directory or that `sys.path` is configured correctly within the notebook.