Hey there... I have been crazy busy and have been long-overdue on upgrading the copy of MC on my Server. I tried a couple weeks ago (multiple times), and I had to roll back.
MC30 (and MC31 at least so far) is corrupting my library such that no client copy of MC can connect properly. When I first do the upgrade, everything is fine. However, after 24-48 hours, then I'll find that none of my client copies of MC (which are all on the latest MC30 build) can properly connect. The behavior, once they're "broken" is:
* The initial connection progress dialog takes much longer than usual (usually it is nearly instant and you only see that dialog for a second or two).
* It goes away as though it connected after 30-45 seconds, and MC's UI never appears.
* If I try to re-launch MC, it complains it is already running.
* The Media Center 30.exe process is running, and usually consuming ~10% CPU, but stays stuck forever.
* All clients of MC are impacted. MC29 copies, MC30 copies, Windows, and macOS.
When it gets into this state, I can "fix" it by restoring the Library it auto-saved (or one I made manually) from right at the time of the upgrade. Then the client copies of MC will connect properly again. (I have to kill the stuck tasks, but upon restart they work fine.) But, unfortunately, the next day I'm right back in the same place (and I lose any play stats for the intervening day).
Looking at the Server, nothing seems to be amiss when in this state. MC quits and relaunches fine, and can browse the Library and play assets. I do see evidence, sometimes, of MC seeming to have had issues "launching" (multiple copies of the same error message about launching with the Library in read-only mode). They weren't there all the time, and I've only seen this twice, so I may have specifics wrong (the family-acceptance of the issue is VERY LOW so I haven't really had much time to keep it in this state and let it corrupt itself and do much testing).
I think the issue is related to one of the scripts I have that does automated maintenance on MC at night, though I haven't been able to determine which one. All of the scripts (there are basically 4 per week) work just fine on MC29. I can post them if you'd like, though you'd need my additional tools and prod's MCiS for all of them to work.
I suspect it is one of the simpler two, though. I ran the more complicated ones manually and the client copies kept working afterwards. The one I'm most suspicious of is my "handheld" syncing script, which is attached (the username/password are edited out, but otherwise it is un-edited).