Yep, that’s a known issue on jupyterlite, which powers some of the demos on jupyter.org: pandas.read_csv("iris.csv") FileNotFound · Issue #119 · jupyterlite/jupyterlite · GitHub
Basically, we need to get the “server contents” into the “virtual machine” where the kernel runs. The reason for the quotes: all of these things are happening in the browser, but there are various boundaries in the way.