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.

When you run the python installer, they display this information to you. It is also documented in /Applications/Python 3.6/ReadMe.rtf, but it's very easily overlooked.

Just browse to Applications/Python 3.6 and double-click Install Certificates.command

There is an issue in the Python bug tracker about this. http://bugs.python.org/issue29480

Update: This issue is marked as resolved in the bug tracker with this text being part of the latest comment:

... For 3.7.0b2, I have tried to make things more obvious in two ways. One, the installer package will now attempt to open a Finder window for the /Application/Python 3.7 folder that contains the "Install Certificates.command". Two, rather than just a generic "installation complete" message at the end of the install, there is now a tailored message that urges the user to click on the "Install Certificates.command" icon. ...

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.

TL;DR

The remote website seems to be the problem, not Python. There is likely no fix for this other than to fix the website.

Longer Explanation

The website/server your are dealing with is apparently configured incorrectly. This has nothing directly to do with Python. That said, you can ignore any certificate errors with e.g.:

r = requests.get(url=URL, params=PARAMS, verify=False)

or you can otherwise try to point Python at the missing certificates (as pointed out by @dave_thompson_085 in the comments).

However, this is unlikely to do any good as the server then apparently responds with a 500: Internal Server Error (verified with curl) and a Content-Length: 0, which would seem to indicate an error in the processing of api.php itself (i.e. there is no JSON to process anyway).

This isn't a solution to your specific problem, but I'm putting it here because this thread is the top Google result for "SSL: CERTIFICATE_VERIFY_FAILED", and it lead me on a wild goose chase.

If you have installed Python 3.6 on OSX and are getting the "SSL: CERTIFICATE_VERIFY_FAILED" error when trying to connect to an https:// site, it's probably because Python 3.6 on OSX has no certificates at all, and can't validate any SSL connections. This is a change for 3.6 on OSX, and requires a post-install step, which installs the certifi package of certificates. This is documented in the file ReadMe.rtf, which you can find at /Applications/Python\ 3.6/ReadMe.rtf (see also the file Conclusion.rtf, and the script build-installer.py that generates the macOS installer).

The ReadMe will have you run the post-install script at

/Applications/Python\ 3.10/Install\ Certificates.command (Terminal App, this command alone should, fix the issue. Be sure to update the file path using your current subversion.)

(its source is install_certificates.command), which:

• first installs the Python package certifi, and
• then creates a symbolic link from the OpenSSL certificates file to the certificates file installed by the package certifi.

Release notes have some more info: https://www.python.org/downloads/release/python-360/

On newer versions of Python, there is more documentation about this:

• https://github.com/python/cpython/blob/e05a703848473b0365886dcc593cbddc46609f29/Mac/BuildScript/resources/ReadMe.rtf#L22-L34
• https://github.com/python/cpython/blob/e05a703848473b0365886dcc593cbddc46609f29/Mac/BuildScript/resources/Conclusion.rtf#L15-L19
• https://github.com/python/cpython/blob/e05a703848473b0365886dcc593cbddc46609f29/Mac/BuildScript/resources/Welcome.rtf#L23-L25
• https://github.com/python/cpython/blob/e05a703848473b0365886dcc593cbddc46609f29/Mac/BuildScript/resources/install_certificates.command
• https://github.com/python/cpython/blob/e05a703848473b0365886dcc593cbddc46609f29/Mac/BuildScript/README.rst
• https://github.com/python/cpython/blob/e05a703848473b0365886dcc593cbddc46609f29/Mac/BuildScript/build-installer.py#L239-L246

For anyone who still wonders on how to fix this, i got mine by installing the "Install Certificates.command"

Here is how I did,

Just double click on that file wait for it to install and in my case, you will be ready to go