If you use MobileMe and take advantage of the option to synchronize your data, like contacts and calendars, you might be aware that Apple has changed something behind the scenes and has asked you to “upgrade” your calendars. What may not be clear is what that means and how best to do it.

Before Apple made their changes a few months ago, a copy of your calendars was stored on each device that had access to them. Every copy was a “master”, and MobileMe just synchronized the changes among them. That worked well enough, but sometimes led to calendars being out of sync, at which time you’d have to reset your calendars using the MobileMe data, or reset MobileMe using your desktop data.

With the new scheme, your calendars are kept at Apple’s servers, and your devices all get their information from them. A local copy is still kept on your devices, but they are not considered the “master”.

This has led to some nice features like the ability to share your calendars with others while optionally giving them the ability to edit. The new format also takes advantage of “push” technology so that changes on one device are available almost immediately on the others.

Until now, this upgrade has been optional, but will be mandatory after May 5, 2011, so it’s best to do it now while you still have a choice. Although Apple has tried to make the process as simple as possible, in my experience, it can be problematic, especially if you have a large number of events in your calendar.

To guard against data loss, follow these steps:

  • Make sure you haven’t done this already. If you’re new to MobileMe, or just want to confirm that you need to do this, look at the list of calendars on the left side of Cal. If your indiidual calendars are listed under the heading of “ON MY MAC”, you need to upgrade. If the heading is something like “ADDRESS@ME.COM”, you’re all set.
  • Review the information that Apple provides. You can start here and see the FAQ here.
  • Update your devices. Before the upgrade, make sure your Macs are running at least OS X 10.5.8, and preferably 10.6.6. Your iOS devices should be upgraded to v.4.2.1. (v.4.3 will be released on Friday, March 11, 2011.)
  • Make sure our devices are all in sync. Be sure to turn on all of your devices and make sure they are connected to the Internet. Enter a test event on one of the devices and make sure it appears on all of them.
  • Backup all of your calendars at once. Go into iCal, go to the File menu and choose Export… -> iCal Archive… Save the file somewhere like your Documents folder. (I create a folder in Documents called “iCal Backups”.) You won’t be needing that file again for this operation, but it’s good to have just in case things go wrong and you have to restore everything to the way it was.
  • Backup your individual calendars. On the left side of iCal, you will see each of your calendars listed individually. Highlight each one in turn and go to the File menu and choose Export… -> Export… and save the file next to the previously saved file. Repeat for each calendar. You will be needing these files later.
  • Backup your entire drive. Whatever your current backup scheme (you do have a current backup scheme, right?), perform it. If you use Time Machine, go up to the Time Machine menu (up near the time in your menubar, the icon that looks like the face of a clock surrounded by a counter-clockwise arrow) and choose “Back Up Now”. Wait until the backup is done.
  • Perform the upgrade. Sign into your MobileMe account at http://www.me.com/calendar. If needed, navigate to the calendars (use the “cloud” that appears at the top, left), and look for the section near the bottom left that offers to upgrade your calendars. Follow the instructions.
  • Wait. This might take a while, and it will warn you of that during the upgrade.
  • Wait some more. If you have a lot of events, the upgrade process might take some time, possibly even a day or two. During that time, you should not enter or edit events in any of your calendars.
  • Check your calendars. After 2 days, check your calendars and see if they look complete. Be sure to look at months in the past as well as the future. If they do, you’re done, and if your Macs are running the latest OS, they will upgrade themselves. If you are using OS X 10.5.8, you will have to follow the directions here.
  • You’ve lost data, so now what? If your calendars are incomplete, you will have to restore them from the individual backups you made. Follow the directions below.
  • Delete the existing calendars. Make note of the name of each the existing calendars that show up under the heading that looks like “ADDRESS@ME.COM”, then delete them all. (Easiest way: Control-click or right-click on each one and choose “Delete”.)
  • Recreate each of the calendars. Use the “+” that appears at the bottom of the list of calendars and give the new ones the same names as the ones you just deleted. Be sure to add these calendars to the “ADDRESS@ME.COM” account.
  • Import your data. Highlight the first calendar, then go to the File menu and choose Import… -> Import… Choose the backup file you created earlier for this individual calendar. On the next screen, make sure it is importing the events into the right calendar.
  • Wait, then repeat. Wait until the import is complete (everything stops spinning), then highlight the next calendar and repeat the previous step, then wait again. Repeat this until all of your calendars have been imported.

Does this seems like a lot of work for something you probably didn’t ask for in the first place? You bet, and I wish Apple had made the process easier, or, at least made it so it worked consistently. As always, if you need help with this process, we stand ready to assist.

[Written by Kem Tekinay]