// add_action( 'http_api_curl', function ( $handle ) {
//     curl_setopt( $handle, CURLOPT_CAINFO, '/home/gnlncom/ssl/cacert.pem' );
//     curl_setopt( $handle, CURLOPT_CAPATH, '/home/gnlncom/ssl/cacert.pem' );
// } );



<pre>PHP version: 5.6.40
cURL version: 8.9.1
SSL version: OpenSSL/1.1.1w

PEM file exists: YES
PEM file readable: YES
PEM file size: 225076 bytes

--- Test WITH cacert.pem ---
Error number: 0
Error message: 
HTTP code: 200

--- Test WITHOUT SSL verify (bypass) ---
Error number: 0
Error message: 
HTTP code: 200

--- PHP curl.cainfo setting ---
curl.cainfo: /home/gnlncom/ssl/cacert.pem
openssl.cafile: /home/gnlncom/ssl/cacert.pem
</pre>