On attempt to install a certificate and a key from files for Linux Shared Hosting website, the following error appears:
"Cannot install host certificate without private key"
This error appears only if certificate or key provided in a file form do not have 'newline' (caret return) symbol between them - at the end of certificate or at the beginning of a key.
RFC 7468 explicitly defines structure of encapsulation boundaries (that's how BEGIN/END are officially named), but end-of-line symbols are optional at the end of the closing boundary.
This issue was reported to the Development team as POA-114512: "Certificate without trailing newline cannot be installed".
As the workaround, you may install certificates from the clipboard or add a newline at the end of the certificate or beginning of the key.
You may contact your Technical Manager or PTA team in order to acquire the status of the issue.