The error message from curl — "failed to verify the legitimacy of the server and therefore could not establish a secure connection to it" — indicates that curl is unable to validate the server’s SSL/TLS certificate. This typically happens when:

• The server’s certificate is self-signed or not signed by a trusted Certificate Authority (CA).
• The certificate chain is incomplete or missing intermediate certificates.
• The certificate does not match the domain name (hostname mismatch).
• The local system’s CA certificates are outdated or missing.
• A proxy or antivirus is intercepting SSL traffic with its own certificate.

How to fix this issue

1. Verify the server certificate Make sure the server is presenting a valid certificate that matches the domain name and is signed by a trusted CA. You can use tools like openssl s_client or online SSL checkers to inspect the certificate. 2. Update your system’s CA certificates On Linux systems, update the CA certificate bundle:

bash

sudo update-ca-certificates

or reinstall CA packages if necessary. On Windows, ensure the root certificates are up to date. 3. Use the--cacert option If you have a custom CA certificate (e.g., for an internal server), specify it explicitly:

bash

curl --cacert /path/to/ca_certificate.crt https://yourserver.com

4. Disable SSL verification (not recommended for production) If you want to bypass the SSL check temporarily (e.g., for testing or development), use the -k or --insecure flag:

bash

curl -k https://yourserver.com

This tells curl to ignore certificate validation errors but reduces security and should be avoided in production environments. 5. Check for proxy or antivirus interference Sometimes local proxies or antivirus software intercept SSL connections and present their own certificates, causing curl to fail verification. Disable such software temporarily or configure curl to trust the proxy’s CA certificate.

Summary

• The error means curl cannot verify the server’s SSL certificate.
• Ensure the server’s certificate is valid and trusted.
• Update your CA certificates or specify a custom CA with --cacert.
• Use -k or --insecure to skip verification if necessary (not secure).
• Check for proxy or antivirus software interfering with SSL.

This approach aligns with guidance from multiple sources explaining the error and solutions, including using curl -k to ignore SSL errors, updating CA certificates, and verifying correct server certificates