[Python] Pip SSL Error on Windows

I use Python 3.x on Windows 7 64 bit in an environment without full control of inbound/outbound traffic processing. Up till this week I've been able to use the --trusted-host pypi.python.org flag with pip and everything worked. This week I have started getting the following error even with the --trusted-host flag.

Could not fetch URL https://pypi.python.org/simple/pytubes/: There was a probl
em confirming the ssl certificate: [SSL: CERTIFICATE_VERIFY_FAILED] certificate
verify failed (_ssl.c:720) - skipping


I tried changing the --trusted-host flag to https://files.pythonhosted.org/packages/ in light of the pypi change this week, but that didn't seem to help.

I also tried downloading and installing the wheels of certifi, wincerstore and win32 certifi as well as other stackoverflow suggestions for this kind of issue such as the digistore .pem cert and pip.ini file without any success.

pip install fails with "connection error: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:598)"

Finally I tried upgrading pip to pip 10 from pip 9.0.3 following the instructions here: https://pip.pypa.io/en/stable/installing/

For the curl download I had to pass -k in, and running python get-pip.py fails with a similar ssl error to pip:

Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)': /simple/pip/
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)) - skipping
Could not find a version that satisfies the requirement pip (from versions: )
No matching distribution found for pip
Could not fetch URL https://pypi.org/simple/pip/: There was a problem confirming the ssl certificate: HTTPSConnectionPool(host='pypi.org', port=443): Max retries exceeded with url: /simple/pip/ (Caused by SSLError(SSLError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:749)'),)) - skipping


Appreciate any suggestions for next steps since the .pem file, Python CA packages and --trusted-host flag didn't do the trick

Edit:

New output with the -vvv flag in pip from an answer below.

> pip install pytubes -vvv
Config variable 'Py_DEBUG' is unset, Python ABI tag may be incorrect
Config variable 'WITH_PYMALLOC' is unset, Python ABI tag may be incorrect
Collecting pytubes
1 location(s) to search for versions of pytubes:
* https://pypi.python.org/simple/pytubes/
Getting page https://pypi.python.org/simple/pytubes/
Looking up "https://pypi.python.org/simple/pytubes/" in the cache
No cache entry available
Starting new HTTPS connection (1): pypi.python.org
Could not fetch URL https://pypi.python.org/simple/pytubes/: There was a probl
em confirming the ssl certificate: [SSL: CERTIFICATE_VERIFY_FAILED] certificate
verify failed (_ssl.c:749) - skipping
Could not find a version that satisfies the requirement pytubes (from versions
: )
Cleaning up...
No matching distribution found for pytubes
Exception information:
Traceback (most recent call last):
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\basecommand.py", line 215
, in main
status = self.run(options, args)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\commands\install.py", lin
e 335, in run
wb.build(autobuilding=True)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\wheel.py", line 749, in b
uild
self.requirement_set.prepare_files(self.finder)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\req\req_set.py", line 380
, in prepare_files
ignore_dependencies=self.ignore_dependencies))
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\req\req_set.py", line 554
, in _prepare_file
require_hashes
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\req\req_install.py", line
278, in populate_link
self.link = finder.find_requirement(self, upgrade)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\index.py", line 514, in f
ind_requirement
'No matching distribution found for %s' % req
pip.exceptions.DistributionNotFound: No matching distribution found for pytubes
Looking up "https://pypi.python.org/pypi/pip/json" in the cache
No cache entry available
Starting new HTTPS connection (1): pypi.python.org
There was an error checking the latest version of pip
Traceback (most recent call last):
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\packages
\urllib3\connectionpool.py", line 595, in urlopen
chunked=chunked)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\packages
\urllib3\connectionpool.py", line 352, in _make_request
self._validate_conn(conn)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\packages
\urllib3\connectionpool.py", line 831, in _validate_conn
conn.connect()
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\packages
\urllib3\connection.py", line 289, in connect
ssl_version=resolved_ssl_version)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\packages
\urllib3\util\ssl_.py", line 308, in ssl_wrap_socket
return context.wrap_socket(sock, server_hostname=server_hostname)
File "C:\ProgramData\Anaconda3\lib\ssl.py", line 401, in wrap_socket
_context=self, _session=session)
File "C:\ProgramData\Anaconda3\lib\ssl.py", line 808, in __init__
self.do_handshake()
File "C:\ProgramData\Anaconda3\lib\ssl.py", line 1061, in do_handshake
self._sslobj.do_handshake()
File "C:\ProgramData\Anaconda3\lib\ssl.py", line 683, in do_handshake
self._sslobj.do_handshake()
ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c
:749)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\adapters
.py", line 423, in send
timeout=timeout
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\packages
\urllib3\connectionpool.py", line 621, in urlopen
raise SSLError(e)
pip._vendor.requests.packages.urllib3.exceptions.SSLError: [SSL: CERTIFICATE_VER
IFY_FAILED] certificate verify failed (_ssl.c:749)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\utils\outdated.py", line
126, in pip_version_check
headers={"Accept": "application/json"},
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\sessions
.py", line 488, in get
return self.request('GET', url, **kwargs)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\download.py", line 386, i
n request
return super(PipSession, self).request(method, url, *args, **kwargs)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\sessions
.py", line 475, in request
resp = self.send(prep, **send_kwargs)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\sessions
.py", line 596, in send
r = adapter.send(request, **kwargs)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\cachecontrol\adap
ter.py", line 47, in send
resp = super(CacheControlAdapter, self).send(request, **kw)
File "C:\ProgramData\Anaconda3\lib\site-packages\pip\_vendor\requests\adapters
.py", line 497, in send
raise SSLError(e, request=request)
pip._vendor.requests.exceptions.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certi
ficate verify failed (_ssl.c:749)

Continue reading...