The problem you are having is caused by an untrusted SSL certificate.

Like dirk mentioned in a previous comment, the quickest fix is setting verify=False:

requests.get('https://example.com', verify=False)

Please note that this will cause the certificate not to be verified. This will expose your application to security risks, such as man-in-the-middle attacks.

Of course, apply judgment. As mentioned in the comments, this may be acceptable for quick/throwaway applications/scripts, but this should really not go to production software.

If just skipping the certificate check is not acceptable in your particular context, consider the following options, your best option is to set the verify parameter to a string that is the path of the .pem file of the certificate (which you should obtain by some sort of secure means).

So, as of version 2.0, the verify parameter accepts the following values, with their respective semantics:

• True: causes the certificate to validated against the library's own trusted certificate authorities (Note: you can see which root certificates (RCs) Requests uses via the Certifi library, a trust database of RCs extracted from Requests: Certifi - Trust Database for Humans).

• False: bypasses certificate validation completely.

• Path to a CA_BUNDLE file for Requests to use to validate the certificates.

Source: Requests - SSL Cert Verification

Also take a look at the cert parameter on the same page.

Notice that you're using HTTPS. As mentioned in the Requests manual

To check a host’s SSL certificate, you can use the verify argument [...] By default, verify is set to True

Here are few ways to fix that:

Update OpenSSL (probably will solve your problem)

Taken from here:

If you encounter one of the following errors:

error:0D0890A1:asn1 encoding routines:ASN1_verify:unknown message digest algorithm
error:0D0C50A1:asn1 encoding routines:ASN1_item_verify:unknown message digest algorithm
The software you are using might be compiled with a version too old of OpenSSL that does not take certificates signed with sha256WithRSAEncryption into account.

It requires at least OpenSSL 0.9.8o for a total management of SHA256. OpenSSl 0.9.7m only assures a partial management, for server mode only.

Check your openssl version by

openssl version
OpenSSL 1.0.1k-fips 8 Jan 2015

If you have a smaller version than OpenSSL0.9.8o, you have to update its version (OS X):

brew update
brew install openssl
brew link --force openssl

If that doesn't work, try this way:

brew uninstall openssl
rm -rf /usr/local/openssl
brew install openssl

• there's an issue with openssl installed before OS X 10.10.3 and reinstalling it fixes it
• these command lines will uninstall openssl, remove its folder from your hard-disk and install it again (the updated version)

Install certifi

Taken from here

By default Requests bundles a set of root CAs that it trusts, sourced from the Mozilla trust store. However, these are only updated once for each Requests version. This means that if you pin a Requests version your certificates can become extremely out of date.

From Requests version 2.4.0 onwards, Requests will attempt to use certificates from certifi if it is present on the system. This allows for users to update their trusted certificates without having to change the code that runs on their system.

For the sake of security we recommend upgrading certifi frequently!

In other word, try to install certifi, if you have Request 2.4.0 or newer:

pip install certifi

Hopefully, this will fix the problem.

Use different version of OpenSSL and Requests

Looking into it using Google, I have found that there is a problem with OpenSSL in Python 2:

• https://github.com/docker/docker-py/issues/465#issuecomment-76520363
• https://github.com/Homebrew/homebrew/issues/38226
• https://github.com/docker/compose/issues/1484

However, I am using Python 2.7.6, Requests 2.2.1 and OpenSSL 1.0.1f 6 Jan 2014 and everything runs correctly.

Pass the certificate

In other cases, you may need to tell requests.get the path to the certificate file, if the host's certificate was signed by you.

requests.get("https://api.github.com/events", verify=True, cert=['/path/to/my/ca.crt'])

Set the verify argument to False (NOT RECOMMENDED!)

In case you want to avoid the certificate verification, you have to pass verify=False to the request.get method.

python -c 'import requests; requests.get("https://api.github.com/events", verify=False)'

or from script.py file:

import requests
res = requests.get("https://api.github.com/events", verify=False)
print res

terminal:

$ python script.py
<Response [200]>

Important: Very bad idea; You can be MITM attacked, which is a critical security vulnerability.