After upgrading to Plesk 12.5 from 12.0.18, some of the certificates are missing.
I ran
# /usr/local/psa/admin/sbin/httpdmng --reconfigure-server
# nginx -t
nginx: [emerg] BIO_new_file("/opt/psa/var/certificates/cert-T5CvaQ") failed (SSL: error:02001002:system library:fopen:No such file or...