When preparing OES2015SP1 for OES2018 upgrade the "Common Server Certificate" as shown by YaST gets "lost" ... overwritten by SAN service.
Exported eDirectory server cert is not accepted for import as "Common Server Certificate".

Steps tested:
  1. Create Server Certificate with YaST CA and install as Common Server Certificate. Result: SAN service overwrites /etc/ssl/servercerts/... on next reboot. These cert and key are o.k. (delivered by Apache) and include the full chain, but "Common Server Certificate" ist empty :-(
  2. Export SSL CertificateDNS via iManager to cert.pfx. Rename to cert.p12 --> Can not be imported via YaST as Common Server Certificate

Thus I can't upgrade to OES2018, as "5.3.5 Ensuring That the Server Has a Server Certificate" in Installation Guide isn't fullfilled.