cURL error 60: SSL certificate: unable to get local issuer certificate - DigiCert

Question

I have a production and a test server. Then I have a 3rd party program with a test and a production environment.

Tests are bond together and productions are bond together.

3rd party production server has a DigiCert Global Root G2 and the test server has a DigiCert Global Root CA.

My servers share the environment configuration and both certificates are in /etc/ssl/certs.

I call it with GuzzleHttp.

$client = new Client([
    'base_uri' => 'www.example.com',
]);

$data = [
    'json' => $jsonData
    'expect' => false,
    'auth' => [username, password, basic]
];

$client->request('POST', 'api/endpoint1', $data);

The production server works fine but the test server throws error cURL error 60: SSL certificate: unable to get local issuer certificate.

There is a certificate chain (not sure how this works):

0 s:/CN=www.example.com
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=RapidSSL RSA CA 2018
1 s:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=RapidSSL TLS RSA CA G1
i:/C=US/O=DigiCert Inc/OU=www.digicert.com/CN=DigiCert Global Root G2

1. I need to find out whose fault is that - mine or 3rd party?
2. How can it be fixed?

Answer 1

The problem was that 3rd party has a problem with the certificate. After fix everything works fine now. So no need to update certificates that were already correct (that was already written in the question).