Whenever I run pip to install the Flask packages like virtualenv in Ubuntu 16.04, I get this error:
pip install virtualenv
I meet the same problem
ERROR: Could not install packages due to an EnvironmentError: [Errno 2] No such file or directory: '/root/anaconda3/lib/python3.6/site-packages/tornado-6.0.4.dist-info/METADATA
then I cd /root/anaconda3/lib/python3.6/site-packages/tornado-6.0.4.dist-info/ && ls
DESCRIPTION.rst LICENSE.txt metadata.json
finally, I did cp metadata.json METADATA
solved the problem.
maybe this is helpful to you.