After updating to Sierra, directly after. The Mac Mail keeps crashing. I am trying to send an email and poof it crashes. It crashes randomly as well. Any way to re-install the app or do something without reseting my Mac?

Crashed Thread:        15  -[ComposeBackEnd _saveThreadUpdateAccount:mailbox:]  Dispatch queue: NSOperationQueue 0x600001648df0 :: NSOperation 0x608001e5b7b0 (QOS: USER_INTERACTIVE)

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

Application Specific Information:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'This method must be called on the main thread'
abort() called
terminating with uncaught exception of type NSException

Log: http://pastebin.com/v2Gvw3J9


3 Answers 3


Have you guys tried Rebuilding the Mailbox?

Mail App -> Mailbox -> Rebuild

enter image description here

  • 1
    Thanks for your comment, I tried everything but I finally ended up installing thunderbird.
    – iordanis
    Commented Oct 13, 2016 at 11:22

Before you reinstall Mail, I would make a new user account and log out of the user with the crashing app.

Then log in with the new user and set up a different email account if possible. (if iCloud is crashing - set up gmail first, etc.) It's less likely the crash is app related and it might be more due to the settings files being corrupt or the actual mail data that is drawn on screen being corrupt.


I started getting this same crash.

Fixed it by:

  1. Removed my Gmail account using the Internet Accounts Settings panel (in System Preferences).
  2. Mail now no longer crashing.
  3. Go back into Mail and add back my Gmail account.

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