I used curl to launch a https request to download the file. I used below command:
curl -v -o Output.pdf https://otherdomain.com/upload/manual-8mm-f35-csii-vdslr-5.pdf
The result I get is:
% Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0* Trying 188.8.131.52... * TCP_NODELAY set * Connected to otherdomain.com (184.108.40.206) port 443 (#0) * Initializing NSS with certpath: sql:/etc/pki/nssdb * CAfile: /etc/pki/tls/certs/ca-bundle.crt CApath: none * Server certificate: * subject: CN=www.otherdomain.com * start date: Aug 01 00:00:00 2018 GMT * expire date: Jul 31 12:00:00 2020 GMT * common name: www.otherdomain.com * issuer: CN=RapidSSL RSA CA 2018,OU=www.digicert.com,O=DigiCert Inc,C=US * NSS error -8179 (SEC_ERROR_UNKNOWN_ISSUER) * Peer's Certificate issuer is not recognized. * stopped the pause stream! 0 0 0 0 0 0 0 0 --:--:-- --:--:-- --:--:-- 0 * Closing connection 0 curl: (60) Peer's Certificate issuer is not recognized. More details here: https://curl.haxx.se/docs/sslcerts.html curl performs SSL certificate verification by default, using a "bundle" of Certificate Authority (CA) public keys (CA certs). If the default bundle file isn't adequate, you can specify an alternate file using the --cacert option. If this HTTPS server uses a certificate signed by a CA represented in the bundle, the certificate verification probably failed due to a problem with the certificate (it might be expired, or the name might not match the domain name in the URL). If you'd like to turn off curl's verification of the certificate, use the -k (or --insecure) option.
Any idea what the problem is and how I can fix it?