Q: Can't save, edit or delete contacts.

Any error message? Are these network (iCloud, Google, etc.) or local ("On My Mac") contacts?

Can you edit the contacts on icloud.com?

And do those changes sync back to the Contacts application?

Please test after taking each of the following steps. Back up all data before you begin.

Step 1

Quit the Contacts or Address Book application if it's running.

Triple-click anywhere in the line of text below on this page to select it:

~/Library/Caches/com.apple.AddressBookSourceSync

Right-click or control-click the highlighted line and select

          Services ▹ Reveal in Finder (or just Reveal)

from the contextual menu.* A folder should open with an item selected. Move the selected item to the Trash.

Repeat with this line:

~/Library/Containers/com.apple.AddressBook

*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination command-C. In the Finder, select

          Go ▹ Go to Folder...

from the menu bar and paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.

Step 2

If you use iCloud, uncheck the box marked Contacts in the iCloud preference pane. Press return to confirm, or click Keep on Mac in the dialog that opens.

If you synchronize contacts with any other network service, disable that synchronization in the Internet Accounts  preference pane.

Step 3

This step applies only if you can launch Contacts. From the list of groups on the left side of the Contacts window, select All On My Mac. If that group doesn't exist or is empty, skip this step. Otherwise, from the menu bar, select

          File ▹ Export... ▹ Contacts Archive...

Save the exported archive to the Desktop.

Step 4

Quit Contacts if it's running. Reveal the following item in the Finder as you did in Step 1:

~/Library/Application Support/AddressBook

If you know when the problem started, and you can restore that folder from an earlier backup without losing any contacts, do so and test. Otherwise, move the folder to the Desktop, leaving the window open for now.

Step 5

Launch Contacts. Your contacts and groups will be gone. If you took Step 3, then double-click the file you created in that step and confirm that you want to import from it. Your contacts and groups will reappear.

Step 6

If you took Step 2, reverse it. Test. If the issue is resolved, delete the AddressBook folder and the archive file on the Desktop and close the open folder window.

Otherwise, quit Contacts again and put the AddressBook folder back where it was, overwriting the newer one that will have been created in its place.

Step 7

Go back to Step 3, but this time choose Export vCard... from the Export menu. Continue as in Steps 4-6. All contacts should be preserved, but you may lose some metadata such as group membership.

Mr. Davis—

Typing new data into or editing a contact became excruciatingly slow immediately after I upgraded from Mavericks to Yosemite. Before upgrading my system, I exported my Contacts in both the .abbu and .vcf formats. Because I don’t sync Contacts via iCloud, AddressBook has been a problem every time I upgrade my system.

I have been searching these forums since my original post, Contacts Slow to a Crawl, etc. went unresolved over a month ago. I followed your instructions above to the letter but there was no improvement. Unless I want to spend 5 minutes creating a new contact, I have to type whatever needs to be entered in TextEdit and paste it into a contact.

A curious discrepancy: the.abbu of “On my Mac” is 10MB larger than the .abbu backup of all contacts although the number of contacts is the same. And yes, I tried importing both of them before writing this reply and there was no difference in the results.

I hope you can help me!

Never mind, Mr. Davis. I think it’s straightened out now. Sorry to bother you.