HTTPS and SSL3_GET_SERVER_CERTIFICATE:certificate verify failed, CA is OK

It's a pretty common problem in Windows. You need just to set cacert.pem to curl.cainfo.

Since PHP 5.3.7 you could do:

1. download https://curl.haxx.se/ca/cacert.pem and save it somewhere.
2. update php.ini -- add curl.cainfo = "PATH_TO/cacert.pem"

Otherwise you will need to do the following for every cURL resource:

curl_setopt ($ch, CURLOPT_CAINFO, "PATH_TO/cacert.pem");

curl used to include a list of accepted certificate authorities (CAs) but no longer bundles ANY CA certs since 7.18.1 and onwards. So by default it'll reject all TLS/SSL certificates as unverifiable.

You'll have to get your CA's root certificate and point curl at it. More details at curl's details on TLS/SSL certificates verification.

Warning: this can introduce security issues that SSL is designed to protect against, rendering your entire codebase insecure. It goes against every recommended practice.

But a really simple fix that worked for me was to call:

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

before calling:

curl_exec():

in the php file.

I believe that this disables all verification of SSL certificates.