This error means that cURL is misconfigured on your server. Most probably curl ssl(or openSSL lib) is broken or it simply can’t find the certificates at the pointed location.Please contact your hosting provider and ask them to turn on or FIX “client side SSL” for your site.

Please note (this is important): This is NOT about expensive and complicated “Server side SSL certificates”. When your site makes a post it acts like a client, not as a server. This is about free client side SSL. Client side SSL are the same SSL certificates that included in any webbrowser and used to access SSL protected websites via https protocol.
More info: https://curl.haxx.se/docs/sslcerts.html
Unlike Twitter or Google+ that could be automatically switched to non-SSL connections in such cases, Facebook and some other networks require to be accessed by SSL at all times.

Also please see here: How to check if curlSSL is working properly

Update 2:

Recently discovered the shellshock vulnerability in bash required an update that has temporarily broken SSL for many servers running PHP around the web. Fix for bash problem done by your server admin could cause “Problem with the SSL CA cert (path? access rights?)” error.

To resolve the issue, you’ll need to restart Apache (or nginx). If that doesn’t fix the problem, you’ll need to restart your entire server.

Update 1:

Possible solution sent by one of our users:

I think I found the solution for the certificate bundle problem, when trying to authorize Facebook. WordPress installs a version of the ca-bundle.crt file by default, that generates the problem. What I did was downloading another certificate from here: https://certifie.com/ca-bundle/ca-bundle.crt.txt When you copy-and-paste this text into Notepad and save it as a .crt file (instead of a .txt file) and reupload this to /wp-includes/certificates, Facebook will authorize correctly. Hope you find this useful as I ran into this several times with SNAP. And it has nothing to do with SNAP at all