When using ansible 2.4.0.0 (macOS) to fix this problem update your library:

pip install --upgrade --user boto3

notice the –user it will update, your local $HOME/Library/Python/2.7/lib/python/site-packages

By using --upgrade it will recreate the site-packages.

Or create PYTHONPATH system variable:

export PYTHONPATH=/usr/local/lib/python2.7/site-packages

paramiko

In case you get this error:

Unicode-objects must be encoded before hashing", "unreachable": true

Try:

pip install --upgrade --user paramiko==2.0.6

To upgrade,reinstall ansible just in case:

pip install --upgrade --user ansible