"No matching distribution found" on all pip installations in PyCharm

Question

I'm on Windows 7 running PyCharm Community Edition 2016.1.2 and Python 3.4.3, and I have the following behavior:

• Installing new packages in PyCharm (from Settings -> Project Interpreter) failed with the error message No matching distribution found for [package name], e.g. No matching distribution found for numpy.
• Updating packages in PyCharm (from Settings -> Project Interpreter) claimed to succeed with a Package successfully installed notification, but did not change the package version in the table (and did not actually do the update).
• Installing new packages on the command line with pip (e.g. pip install numpy failed with the same error message as PyCharm.
• Updating packages on the command line gave the output Requirement already up-to-date and no update.

What????

Answer 1

This is pip's behavior when it can't connect to the internet properly. In my case, I had Fiddler running so pip couldn't get through Fiddler's proxy.

To anyone else getting this behavior: check your network, firewalls, proxies, and so on.