PHP cURL Error

[nolanmaris]

Hello

I am facing an issue with cURL in my PHP application. When trying to make a secure HTTPS request, I am getting the following error:

cURL error: SSL certificate problem: unable to get local issuer certificate

Details:

• Server Environment: Apache on Ubuntu 20.04
• PHP Version: 7.4
• cURL Version: 7.68.0

Code Snippet

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://api.example.com/data");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$response = curl_exec($ch);
if (curl_errno($ch)) {
echo 'cURL error: ' . curl_error($ch);
}
curl_close($ch);


I haveverified that the SSL certificate is valid and not expired. Downloaded and updated the cacert.pem file from cURL's website and configured php.ini:


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

Checked the server's openssl version and it is up-to-date.

How can I resolve the "unable to get local issuer certificate" error in cURL?
Are there any additional configurations I need to make in php.ini or my server environment?

Any suggestions on how to solve this SSL issue would be greatly appreciated.



Thank you in advance for your help!



Best regards,
nolanmaris

[YangtuchXo]

Hi Nolan,

The "unable to get local issuer certificate" error usually indicates cURL can't verify the chain of trust for the server's certificate. Here are some troubleshooting steps:

1. Intermediate Certificates: The server might use intermediate certificates to link its certificate to a trusted root CA. Ensure your cacert.pem includes all necessary intermediate certificates. You can download them from the server's certificate authority.
2. Verify Certificate Chain: Manually download the server's certificate and use openssl verify to verify the chain with your cacert.pem. This helps identify missing intermediate certificates.
3. cURL Verification Flag: Try setting CURLOPT_SSL_VERIFYPEER to false (not recommended for production) to bypass verification temporarily. This can confirm if the issue is with certificate trust.
4. Server Configuration: If the issue persists, consult the server administrator. The server might have misconfigured certificates or an outdated certificate chain.

Hopefully, these steps help you identify the missing piece in the certificate chain and resolve the cURL issue.

Good luck!