iCloud: Advanced Calendar and iCal troubleshooting

Calendar (or iCal) may contain duplicates and other unusable data that could prevent iCloud Calendar from displaying and syncing properly. Follow the steps below If you're experiencing an unresolvable issue with your iCloud data in Calendar (or iCal) that you have isolated to your calendar data.

This article has been archived and is no longer updated by Apple.

If you follow the steps and troubleshooting methods discussed in this article, you should be able to resolve most issues with iCloud Calendar.

If after following those methods, you still have issues in Calendar (or iCal) that you know are related to your calendar data itself, the article below discusses additional steps you can take. You should avoid using the steps in this article unless you have:

  1. Verified the issues that you are seeing are specific to your calendar data and your Mac.
  2. You've tried all the troubleshooting methods discussed in Get help using iCloud Calendar.

You should perform the steps in this article from your computer with the most up-to-date calendar data.  

Note: Remember to test to see if the issue you are experiencing still occurs after these steps.

Analyze the state of your calendar data

Review the information in the article iCloud: Using iCloud Calendars with Calendar and iCal, and then look over your calendars. Some of the actions you take will vary depending on where the affected calendars are stored. The most common causes for data-based issues with Calendar are:

  • Unreadable or incompatible calendar data.
  • Reoccurring calendar events that have no end date (such as birthdays).
  • Duplicate events.
  • An excess of calendar events that happened in the past (especially those that were previously synced from another calendar client).

Any of these conditions could be the cause of your issues with Calendar in OS X (or iCal) and iCloud. The steps below will help you determine if any of your calendar data falls into these categories and will help you resolve any related issues.

Back up your Calendar & Reminders data

First, back up your calendars and reminders by following the steps in Archive or make copies of your iCloud data. It's very important that you back up your data prior to following the steps in this article as they involve deleting and modifying your data. If you delete your data, as recommended at points in this article, you will not be able to recover it, unless you have backed up your data.

You should back up each calendar one at a time, including all the calendars in the ICLOUD section, as well as all the calendars in the ON MY MAC section of the calendar list in Calendar (or iCal).

Note: You may only have an ICLOUD section, but in some cases you could have both ICLOUD and ON MY MAC. 

You should back up any calendars that you have been attempting to import or move to iCloud. To help keep track of these you should consider storing the exported ICS files in a uniquely named folder, such as "my Calendar backups," so that you can easily find it later and avoid confusing it with any other exported calendars. Likewise, if you are exporting your Reminders, they should also be saved to their own uniquely named folder. Feel free to make additional backups at any time while following this process.

Temporarily disable any non-Apple calendar accounts

If you are using any calendar accounts besides your iCloud account, such as Microsoft Exchange, Google Calendar, and others, temporarily disable these accounts so that they are not a distraction and you can avoid accidentally modifying their data while performing any of the large scale modifications described in this article.

To disable an account in Calendar (or iCal):

  1. Choose Calendar (or iCal) > Preferences, and then click Accounts.
  2. Select the accounts you wish to temporarily disable in the Account sidebar.
  3. Deselect the checkbox next to "Enable this Account" in the Account Information tab.

Turn off iCloud Calendar

In order to clean up your Calendars and eventually send new, clean data to iCloud, you should temporarily disable iCloud Calendar. Then, you can reimport and clean your calendars. When you clean your calendars locally, you don't have to interact with iCloud until you are ready.

Warning: It is important that you have your iCloud Calendar data backed up from both icloud.com/calendar, Calendar (or iCal), and the Reminders application (or the Reminders section of iCal) prior to disabling iCloud Calendars & Reminders on your computer.

  1. Verify you have backed up both your iCloud and local Calendars and Reminders data by following the instructions in Archive or make copies of your iCloud data.
  2. Open System Preferences.
  3. Click iCloud.
  4. In the iCloud Preference pane, deselect the checkbox next to Calendars & Reminders.
  5. When prompted, choose to remove your iCloud Calendars & Reminders from your computer.

Import any calendars you wish to use with iCloud

After you disable iCloud Calendar, you need to reimport the Calendars you backed up earlier. Reimport any calendars you want to use with iCloud.

  1. In the Finder, open the folder of calendars you exported in Section 2.
  2. Double-click one of the calendars you exported earlier.
  3. Calendar (or iCal) will prompt you with a dialog entitled "Adding new events."
  4. In the "Adding new events" window, select a Destination folder for your calendar import. In most cases you should choose New Calendar from the calendar menu.
  5. Repeat steps 2-4 to import each of the Calendars you exported earlier and want to use with iCloud

Remove unusable and duplicate events

Duplicate events, especially those that occurred in the past, can slow down Calendar (or iCal) particularly when syncing with iCloud. You can use some simple tricks in iCal to find and remove duplicated data.

  1. Open Calendar (or iCal).
  2. Type a period in the Search field located in the top-right corner.
  3. All of your calendar events will appear in the search results, located in the side of the Calendar window (or bottom of the iCal window). Depending on how many events you have, it may take a few minutes for all of them to display.
  4. Scroll through the events. Remove any events that do not have titles by selecting them, and choosing Delete from the Edit menu.
    • You can select consecutive items by holding down the Shift key while selecting them. You can select non-consecutive items by holding down the Command key while selecting them.
  5. Remove any obvious duplicate events. You may want to retain a single version of a duplicate event, but you should remove unwanted versions.
  6. Look for any events whose titles contain complicated characters or symbols. These include high ASCII or double-byte (Unicode) characters (such as Japanese, Chinese, Korean, Emoji, or other extended ASCII characters). Try removing these characters or substituting them with simpler characters. For example, if you had an event titled " Store Appointment" rename it to "Apple Store Appointment".
  7. Click the Date field in the search results to sort by date.
  8. Scroll through the events and scan for duplicates again. In many cases, it will be easier to locate duplicate events that exist on the same day.
  9. Delete any duplicate events by selecting them and choosing Delete from the Edit menu. You may want to retain a single version of a duplicate event, but unwanted versions should be removed.

Note: If you have a large number of duplicates that would be overly time consuming to clean up by hand, you may want to use a third party utility such a BusycalCalendar Cleaner, or iCal Dupe Deleter. For information about how to use these applications, refer to their built-in help or contact the vendor.

Clean up birthdays and use the Birthday Calendar

Birthdays that you manually entered in Calendar (or iCal) can sometimes result in issues, such as infinitely repeating events that can cause slowness and contribute to unnecessary resource utilization in Calendar (or iCal).

While you can add birthdays to any calendar in Calendar (or iCal), it's better to use the Birthdays Calendar. The Birthdays Calendar is a calendar that is automatically created from the birthday information found in Contacts (or Address Book). It's easy to update the Birthdays Calendar by updating your Contacts (or Address Book) with the birthday for each contact. The Birthdays Calendar is enabled by default on iOS. For more information about the Birthdays Calendar, see iCloud: Show the Birthdays calendar and Mac Basics: Address Book.  

To clean up issues related to manually adding birthdays to a calendar in Calendar (or iCal):

  1. If you already have the Birthdays Calendar enabled, deselect it in the Calendars list in Calendar (or iCal).
  2. Search Calendar (or iCal) by entering "birthday" (without the quotes) in the Search dialog in the top-right corner of the Calendar (or iCal) window.
  3. Sort the Search results by title, so they are easier to analyze.
  4. Locate any birthdays that are returned in the Search results that are not contained in a Holidays Calendar (such as John F. Kennedy's Birthday, Lincoln's Birthday, and so on).
  5. For each non-Holidays birthday returned, decide if you want to keep it. If so, open Contacts (or Address Book) and verify that you have a Contact for the individual. Enter the birthday information for that person in Contacts (or Address Book). For more information about updating Contacts (or Address Book) fields, see this article
  6. After verifying that the birthday is entered in Contacts (or Address Book), remove any birthday events not stored in the Birthdays or Holidays calendars by selecting them and choosing Delete from the Edit menu.
    • Note: You can select consecutive items by holding down the Shift key while selecting them. You can select non-consecutive items by holding down the Command key while selecting them.

After cleaning up any manually added birthdays, you can enable or re-enable the Birthdays Calendar. To enable the Birthdays Calendar for the first time, open Calendar (or iCal) > Preferences and select the checkbox next to Show Birthday's Calendar. If you temporarily hid the Birthdays Calendar as per the instructions above, you can re-enable it by selecting the checkbox for it in the Calendar List.

Backup your calendar data (again)

After spending time cleaning up your Calendars, you should back up your calendars with the method discussed below. Though this may seem like extra work, you should create a backup of your calendar set, so you have something to revert to if an issue occurs.

  1. Create a new folder on your Desktop entitled "cleaned calendars."
  2. Open the Calendar List in Calendar (or iCal).
  3. Select the first Calendar in the list.
  4. Choose File > Export > Export.
  5. When prompted to save the Calendar as an ICS file, retain its current name, and choose to save it to your "clean calendars" folder on your Desktop.
  6. Move on to the next calendar, and repeat steps 4 and 5 for it. Continue until you have exported all your Calendars from Calendar (or iCal).

Re-enable iCloud Calendar

After you have cleaned and backed up your calendars, you should re-enable iCloud Calendar:

  1. Verify that you have backed up both your iCloud and local Calendars and Reminders data by following the instructions in Archive or make copies of your iCloud data.
  2. Open System Preferences.
  3. Click iCloud.
  4. In the iCloud Preference pane, select the checkbox next to Calendars & Reminders.

Your calendars should now be moving between Calendar (or iCal) and iCloud without issues. If you disabled any non-Apple calendar accounts through the course of troubleshooting, you can re-enable those at this time.

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