Q: imessage problem on 2009 Mac Pro

Please read this whole message before doing anything.

This procedure is a diagnostic test. It won’t solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.

The purpose of this test is to determine whether the problem is localized to your user account. Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”

While logged in as Guest, you won’t have access to any of your documents or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this behavior; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.

Test while logged in as Guest. Same problem?

After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.

*Note: If you’ve activated “Find My Mac” or FileVault in OS X 10.7 or later, then you can’t enable the Guest account. The "Guest User" login created by "Find My Mac" is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.

Launch the Console application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

The title of the Console window should be All Messages. If it isn't, select

          SYSTEM LOG QUERIES ▹ All Messages

from the log list on the left. If you don't see that list, select

          View ▹ Show Log List

from the menu bar at the top of the screen.

Click the Clear Display icon in the toolbar. Then try to send a message. Select any lines that appear in the Console window. Copy them to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

The log contains a vast amount of information, almost all of which is irrelevant to solving any particular problem. When posting a log extract, be selective. A few dozen lines are almost always more than enough.

Please don't indiscriminately dump thousands of lines from the log into this discussion.

Please don't post screenshots of log messages—post the text.

Some private information, such as your name or email address, may appear in the log. Anonymize before posting.

Back up all data.

Quit Messages if it’s running. Force quit if necessary. Relaunch it and test after each of the following steps. If the problem isn't resolved, quit again and go on to the next step.

Step 1

Make sure you know the ID and password you use with iMessage. Launch the Keychain Access application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad and start typing the name.

Select the login keychain from the list on the left side of the Keychain Access window. If your default keychain has a different name, select that.

If the lock icon in the top left corner of the window shows that the keychain is locked, click to unlock it. You'll be prompted for the keychain password, which is the same as your login password, unless you've changed it.

From the menu bar, select

          Keychain Access ▹ Keychain First Aid

from the menu bar and repair the keychain.

From the Category list in the lower left corner of the window, select

           My Certificates

Look carefully at the list of certificates in the right side of the window. If any of them is marked with a red "X" as expired or invalid, delete it. Also delete all items with "iMessage" or "com.apple.idms" in the name, whether valid or not.

Now select

            Passwords

in the Category list. Enter "ids" (without the quotes) in the search box in the toolbar of the window. Delete all items of type "application password" that have a name beginning in any of the following ways:

            ids:

            IDS:

            com.apple.ids:

Quit Keychain Access. Log out and log back in.

Step 2

Hold down the option key and select

          Go ▹ Library

from the Finder menu bar. Move the following items from the Library folder to the Trash (some may not exist):

          Containers/com.apple.corerecents.recentsd

          Caches/com.apple.Messages

          Caches/com.apple.imfoundation.IMRemoteURLConnectionAgent

          Containers/com.apple.iChat

          Containers/com.apple.soagent

          IdentityServices

Leave the Library folder open. Log out and log back in.

Step 3

Go back to the Finder and move the following item from the open Library folder to the Desktop:

          Messages

Note: you are not moving the Messages application. You’re moving a folder named “Messages.”

If Messages now works, delete the Messages folder on the Desktop. Otherwise, quit Messages again. Put back the folder you moved, overwriting the newer one that may have been created in its place.

Step 4

In the Preferences subfolder, there may be several files having names that begin with any of the following strings:

          com.apple.iChat

          com.apple.ids

          com.apple.imdsmsrecordstore

          com.apple.imessage

          com.apple.imservice

Move them all to the Desktop. There may also be a file with the name "com.apple.imagent.plist". Move that to the Trash.

Also in the Preferences folder, there's a subfolder named "ByHost". Open it and do the same thing.

Log out and log back in. Test again. This time Messages should perform normally, but your settings will be lost. You may be able to put back some of the files you moved to the Desktop in this step. Relaunch and test after each one. Eventually you should find one or more that causes Messages to malfunction. Delete those files and recreate whatever settings they contained.

If the issue is still not resolved, quit Messages again and put all the items you moved to the Desktop back where they were. You don’t need to replace the items you moved to the Trash. Stop here and post your results.

If you later decide that you don’t like the results of Steps 3 and 4, you can undo them completely by quitting Messages and restoring the items you deleted in those steps from your backup.

Please sign out of iCloud in its preference pane and see whether there's any change. No data will be removed from the servers, and you can retrieve it by signing back in. That said, you should always have a current archive of the data for safety's sake, even if you don't sign out.

If you use iCloud Keychain, when you sign back in to iCloud follow one of the procedures described in this support article to set it up on an additional device.