When using pathlib, getting error: TypeError: invalid file: PosixPath(‘example.txt’)

pathlib integrates seemlessly with open only in Python 3.6 and later. From Python 3.6’s release notes:

The built-in open() function has been updated to accept os.PathLike objects, as have all relevant functions in the os and os.path modules, and most other functions and classes in the standard library.

To get it to work in Python 3.5 and Python 3.6, just convert the object to a string:

contents = open(str(filename), "r").read()