Error: ssl certificate key pair is not valid

The latest version 1.6.14. Recently I keep getting “Error: ssl certificate key pair is not valid” whenever I try to insert new SSL certificate via Control Panel and Command line(v-add-web-domain-ssl USER DOMAIN SSLDIR). I searched and read some threads mention about solution in 2019 about updating OpenSSL but system already had the latest OpenSSL 1.1.1f 31 Mar 2020. Another system of mine running the same version of Hestia and OpenSSL but on ARM processor, accept new SSL certificate without problem. Any log can I troubleshoot? Is there workaround for this issue?