The new requirements for an SSL certificate to be accepted by iOS 13 and macOS 10.15 are given in In the following, mercury is the new hostname for the CentOS server, which can then be reached at the domain name mercury.local from any device on the local network. The easiest solution was to use avahi, a library that gives functionality equivalent to Apple's Bonjour software. That became even more problematic with the new systems. Create local domain nameĮven previously, it was somewhat problematic to refer to the Calendar/Contacts/Mail server only by a local IP address (e.g., 172.16.1.123) instead of by a domain name. The following describes changes to the previous instructions needed to get things working again. See the Apple support document, (cheerfully titled, 'Get ready for the new Reminders app') which gives the official bad news. The most appalling change is that the Reminders app is not backwards compatible, and if you have any mix of devices running either of those new versions along with any device running pre iOS 13 or pre macOS 10.15, then shared Reminders is completely non-functional. As a side note, I recommend avoiding upgrading to iOS 13 or macOS 10.15 if at all possible.
