Hello and welcome.
Due to the Beta licensing from Apple, we cannot support that version of OS X. If this is regarding a beta version of iTunes, the same would hold true. And, if it is a beta, then you will experience issues like this from time to time - hence the term beta software. There are official
Apple Developer Forums where you can post questions and concerns with their yet unreleased software.
However, this has been an issue for some in the past:
iTunes can’t verify the identity of the server
We strongly encourage everyone to have a current Time Machine or other backup of their data at all times, and to never run best software on your main Mac. You should always have a dedicated Mac, or at least a dedicated hard drive for testing purposes.
C