Xiang Zhang added the comment: No, urllib.request does not handle the no_proxy environment in case-sensitive way. It first checks if any environment_variable.lower() ends with "_proxy", and then checks if there is any environment_variable ends with "_proxy". So it works as a case insensitive check, but the lowercase one will override others, e.g, no_proxy overrides no_PROXY. But the document is misleading, it should be clarified. ---------- assignee: -> docs@python components: +Documentation -Library (Lib) nosy: +docs@python, martin.panter, xiang.zhang _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue26864> _______________________________________