When using DigiCert for certificate generation, they will supply you with a .CER or .CRT certificate file as the default.


The Titan/Cornerstone Certificate Management system requires a .PEM file format when Updating the CSR and attaching the certificate.


To acquire a .PEM formatted certificate from DIgiCert, review the process on the DigiCert website.


Note: when given the options for downloading a PEM file, choose "Single PEM File Containing Only The End Entity Certificate"


https://www.digicert.com/ssl-support/pem-ssl-creation.htm