PHP - SSL certificate error: unable to get local issuer certificate

Finally got this to work!

1. Download the certificate bundle.

2. Put it somewhere. In my case, that was c:\wamp\ directory (if you are using Wamp 64 bit then it's c:\wamp64\).

3. Enable mod_ssl in Apache and php_openssl.dll in php.ini (uncomment them by removing ; at the beginning). But be careful, my problem was that I had two php.ini files and I need to do this in both of them. One is the one you get from your WAMP taskbar icon, and another one is, in my case, in C:\wamp\bin\php\php5.5.12\

4. Add these lines to your cert in both php.ini files:

   curl.cainfo="C:/wamp/cacert.pem"
   openssl.cafile="C:/wamp/cacert.pem"
   

5. Restart Wamp services.

Editor's note: disabling SSL verification has security implications. Without verification of the authenticity of SSL/HTTPS connections, a malicious attacker can impersonate a trusted endpoint (such as GitHub or some other remote Git host), and you'll be vulnerable to a Man-in-the-Middle Attack.

Be sure you fully understand the security issues before using this as a solution.

I had the same problem in Mandrill.php file after line number 65 where it says $this->ch = curl_init();

Add following two lines:

curl_setopt($this->ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($this->ch, CURLOPT_SSL_VERIFYPEER, 0);

This solved my problem and also sent email using localhost but I suggest to NOT use it on live version live. On your live server the code should work without this code.