Python Testing with pytest, Second Edition: InterpreterNotFound error when running tox (page 150)

When running tox for the first time, I got the following error:

ERROR: InterpreterNotFound: python3.10

I realised that I was running it in a python 3.8 virtual env so got out of the virtual env, ran it and it passed. It would be good to explain to the reader that this can happen and how to solve it if it does.