I inherited a mid to late Mac-mini server now running Sierra. Can I upgrade to High Sierra? I know it's old but it's a Mac, it still works wonderfully has 16GB memory and plenty of storage. Give me good news.
Yes, see > How to upgrade to macOS High Sierra - Apple Support
If you want to keep using it as a server?
see the last paragraph at > Upgrade and migrate data on your macOS Server - Apple Support
Yes, see > How to upgrade to macOS High Sierra - Apple Support
If you want to keep using it as a server?
see the last paragraph at > Upgrade and migrate data on your macOS Server - Apple Support
2011 Mini MAC SERVER UPDATE TO HIGH SIERRA?
