Calendar doesn't sync, error message

I got the attached error when trying to add a .ics file event to my calendar.




I have a MBP with Maverics, fully updated, a mini iPad and an iPhone 5s, both running IOS 7.1. I had entered the .ics on my iPhone when the email with it arrived, expecting it to sync to my iPad and MBP, but it didn't. So I went to my iCloud account, opened Calendar there and dropped the .ics file on Calendar. The appointment appeared on my Calendar, followed by that error message. I searched for a solution, but although some folks suggested various things at Apple.com support, the problem is persistent. So, before I engage Apple tech support, does anybody here have any idea what to do? I've tried deselecting and reselecting Calendars on my MBP System Preferences for iCloud, but when I did that, the events on my MBP Calendar refreshed and the error reappeared. Did the same on my iPad and iPhone. The event won't sync to them, so I've entered it on each device just to get it recorded.

So, how do I 1) get rid of the error and 2) sync calendars using iCloud reliably?

Does it sync reliably when you just enter a Calendar event manually on any of your devices?

I've gotten a few .ics files in email, but just double-clicking them worked for me.

Yes, if I create the appointment myself, it will sync across machines, no matter where it is first created. I'm still getting the error message, now appearing on my desktop whenever an iCloud sync occurs. I don't get many .ics files, so this is new.

It could be an invalid ics file. You can try the validator here to see if that is indeed the case.

I just did that and got confusing results: "Your calendar is using an invalid newline format. Make sure to use \r\n to end lines rather than just \n (RFC 2445 §4.1).
Congratulations; your calendar validated!"

So, it's right and it's wrong. Valid and invalid.

I saw someone post a similarly confused response and the conclusion in that discussion was that it was fine but that it had some oddities.

So, that CalDAV error is a bit nebulous but it does seem to have to do with queuing. Perhaps the task is trying to be added to a space in your calendar but is stuck behind the other one that you added manually (or on your iPhone). Maybe the sync is just slow and Calendar knows it. Indeed, various examples of this error online suggest that the error goes away after a while.

Well, the error message hasn't appeared in a while, but the appointment didn't sync. I manually entered the data on my iPhone and it synced over to the iPad and to the MBP, but the .ics appointment won't. The appointment is today, so to get rid of the message I'll just delete the .ics appointment, but it's annoying that Calendar doesn't want to accept an ics invitation.

This appears across various services (I saw some references to Google's CalDAV service) so I think this might be an unavoidable flaw of CalDAV.