When you execute PHP CURL calls to HTTPS URLs, you might get the following error:

SSL certificate problem: unable to get local issuer certificate

This means that the root certificates on the system are invalid.

You have 3 different ways to proceed:

• Maintain SSL enabled – change php.ini:
  • Downloaded cacert.pem from http://curl.haxx.se/ca/cacert.pem
  • Copy cacert.pem to ‘/usr/local/openssl-0.9.8/certs/cacert.pem’  // Or whatever version of openssl / zend you have.
  • Modify CURL configuration on your php.ini file:
    • Below [curl] add => cainfo = ‘/usr/local/openssl-0.9.8/certs/cacert.pem’
  • Restart PHP and check if CURL can read from HTTPS URL.

• Maintain SSL enabled – do not change php.ini:
  • Use the following code to use the credentials you got on the previous step:
    
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    $ch = curl_init(); $certificate_location = '/usr/local/openssl-0.9.8/certs/cacert.pem'; curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, $certificate_location); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, $certificate_location);

• Disable SSL – NOT RECOMMENDED:
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    $ch = curl_init(); curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0); curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);