curl: (60) SSL certificate problem: unable to get local issuer certificate

Relating to 'SSL certificate problem: unable to get local issuer certificate' error. It is important to note that this applies to the system sending the CURL request, and NOT the server receiving the request.

1. Download the latest cacert.pem from https://curl.haxx.se/ca/cacert.pem

2. Add the following line to php.ini: (if this is shared hosting and you don't have access to php.ini then you could add this to .user.ini in public_html).

   curl.cainfo="/path/to/downloaded/cacert.pem"

   Make sure you enclose the path within double quotation marks!!!

3. By default, the FastCGI process will parse new files every 300 seconds (if required you can change the frequency by adding a couple of files as suggested here https://ss88.uk/blog/fast-cgi-and-user-ini-files-the-new-htaccess/).

It is failing as cURL is unable to verify the certificate provided by the server.

There are two options to get this to work:

1. Use cURL with -k option which allows curl to make insecure connections, that is cURL does not verify the certificate.

2. Add the root CA (the CA signing the server certificate) to /etc/ssl/certs/ca-certificates.crt

You should use option 2 as it's the option that ensures that you are connecting to secure FTP server.

I have solved this problem by adding one line code in cURL script:

curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);

Warning: This makes the request absolute insecure (see answer by @YSU)!