pip cannot confirm SSL certificate: SSL module is not available

Question

I am trying to install openCv for Python 3.6 on my Raspberry Pi 3 Model B+, but somehow it won't connect to the python.org website. I have pip installed for 2.7, 3.0, and 3.6 installed, so when I go and do something like:

pip3 install opencv-python

I get this error:

pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Collecting opencv-python
  Could not fetch URL https://pypi.python.org/simple/opencv-python/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
  Could not fetch URL https://www.piwheels.org/simple/opencv-python/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
  Could not find a version that satisfies the requirement opencv-python (from versions: )
No matching distribution found for opencv-python

I can access the website perfectly on my desktop and phone, but my Raspberry Pi won't at all. Any idea what I can do?

Answer 1

pip3 missed a certificate for authentication to https://pypi.python.org/simple/opencv-python/ and to https://www.piwheels.org/simple/opencv-python/. On my RasPi (Raspbian Stretch) I found two packages in its repository with apt list *certi* that may belonging to it:

ca-certificates/stable,now 20161130+nmu1+deb9u1 all [installed]
python3-certifi/stable 2016.2.28-1 all

You can try to install them but I don't know if it helps:

rpi ~$ sudo apt update
rpi ~$ sudo apt full-upgrade
rpi ~$ sudo apt install ca-certificates python3-certifi

Answer 2

You need to install following dependencies.

Run in following in your terminal

sudo apt-get install build-essential checkinstall 
sudo apt-get install libc6-dev libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libbz2-dev