iPhone Calendar not syncing to iCloud yet iCloud syncs to iPhone

You'll probably have to go through an add missing events from your phone to your iCloud calendars on icloud.com, even if it's difficult to determine which events are missing.

Most of the time these problems are resolved by making sure you default calendar is and iCloud calendar, adding any missing calendar events from your phone to your calendars on icloud.com, then going to Settings>iCloud, turning Calendars to Off, choosing Delete from My iPhone when prompted (they will still be in iCloud), then after a minute or so, turning Calendars back to On.

I'm not sure it will make any difference but this has a 90%+ success rate in restarting calendar syncing. Also, if it doesn't fix things, the next thing you'll have to do is try restoring your phone. Unfortunately, Apple's documention on the iCloud backup doesn't clarify whether or not it backs up calendar events so prior to restoring your phone you'll want to be sure your calendars in iCloud are up to date with your iPhone calendars. This way, you aren't relying on the backup to restore your calendars after restoring your phone; they will be synced back to your phone from your iCloud account. In other words, I don't see a path to resolving this that doesn't require you to update the calendars on icloud.com.

You can look throught the troubleshooting steps here under "Troubleshooting iOS devices": http://support.apple.com/kb/TS3999, but I think you've already done most or all of that already. If so, the only thing left to try is restoring your phone.

Before restoring your phone, create a current backup. I would back up both to iCloud and using iTunes so you have a second backup in case one fails. If you're backing up to iCloud now, you can still perform a manual backup in iTunes by going to the Summary tab of your iTunes sync settings and Clicking on Back Up Now. While there, go to File>Devices>Transfer Purchases to transfer any recent purchases to your iTunes library. I would also recommend importing your camera roll photos and videos to your computer as explained here: http://support.apple.com/kb/HT4083. This is a precaution because a number of users report that their photos are not restored from from their iCloud backup.

After doing this, connect your phone to your computer and go to the Summary tab of your iTunes sync settings and click Restore iPhone to restore it. When it's done restoring, it will restart and reappear in iTunes and ask if you want to restore to an existing backup. If you backed up to iTunes, choose to restore from backup and choose the backup you made prior to restoring to restore to.

Hopefully your calendars will sync properly after doing all this. If they don't, make an appointment with the Genius bar at a nearby Apple store and let them look at it. Since it was replaced in April, it should still be under warranty and they may decide to replace it again.

Good luck!

You're welcome, glad things are working again. I don't work for Apple; everyone here is just a user who volunteers to help with support issues.

Also, the reason for going through the extra work to update the calendars on icloud.com is that Apple's documentation on what is included in the iCloud backup does not specify that it includes calendar events. Thus, having iCloud up to date insures you don't lose anything in case the backup doesn't restore them.

Unfortuately the 'restore phone' solution from randers4 didn't work for me.

I tried restoring the phone but the same issue persists.

Events created on the iPhone will not sync to iCloud

Events created on my Macbook do sync to iCloud

Events created on iCloud do sync to the Macbook

So the phone is still the issue. It has been working fine for months and has suddenly started doing this.

I am not aware of making any other changes to my settings, so don't know why this has started happening.

Wish Apple would put more resource into making their software work instead of the next hardware release.

The only thing that worked for me was going into iCloud on phone, turning Calendar off, then click Delete from Phone. Wait a few minutes and turn Calendar back on and once it is all loaded, everything worked perfectly. Hope this helps.

Did you try updating the calendars on icloud.com with any missing events from your phone, then going to Settings>iCloud, turning Calendars to Off, choosing Delete from my iPhone when prompted, then turning Calendars back to On after a minute or so?

I had these same symptoms: iCloud additions and changes were sycing down from iCloud to my iPhone, but new events added on the iPhone were not syncing up to iCloud.

Turning iCloud calendars off on my phone and then on again fixed the problem, thanks randers4.

One warning: I have a slightly odd setup, which I forgot about when I did this (though I don't think it would have changed any of the steps to fix it). In addition to several iCloud and MS Exchange calendars, I have one local calendar that syncs with Outlook on my PC (via iTunes) over the USB cable, i.e., the old-fashioned way. This was an archive calendar that held appointments from many years ago, which I like to go back and look at from time to time (even though the #$%!& Calendar app won't search them—my old Palm OS devices would search years back, but noooo, Apple won't—). Anyway, when I turned iCloud calendars back on, it merged that local calendar up to iCloud and got rid of the local version of it (which I didn't want—I took all those old appointments out of the cloud for performance reasons). So, I've deleted that archive calendar from iCloud, and when I get home tonight I'll have to be careful about how I do the sync with my PC to re-establish the arrangement I had before. I'll make sure I have a backup of the data in a separate folder in Outlook, tell iTunes not to automatocally sync when I plug in the phone, then plug in the phone and look at the sync settings and go from there.

My problem was exactly the same, and a whole lot simpler to correct! Perhaps this will help others. Context: All my syncing setting were fine, nothing weird anywhere, all software up to date. Yet, my most recent iPhone appointments weren't syncing to my iMac, but a test appointment entered into my iMac synced perfectly with my iPhone! Just weird. So, much researching on these fora did not yield anything, just these high tech suggestions I did not want to do. Just by fiddling, I fixed my problem myself.

I opened one of the unsynced appointments on my iPhone in day view and upon touching it, [on the screen] a new screen came up, with an option that said "Ctoalendar >". Touching on this gave me 6 options of calendars. 3 each of " on my iPhone" and "iCloud". By assigning this appointment to an iCloud calendar [I chose the "calendar" option of the 3 options, the other two being "work" and "home".

Problem solved.

I think all my unsynced appointments need to be individually changed, but the ones I have done have all synced to the Mac. How the default setting went from 'iCloud' to 'On this iPhone' I know not, but this certainly solved it for me.

Good luck.