Our Exchange server was rebuilt following a hardware failure and this has resulted in the mailbox ID changing. Mail.app doesn't like this, and crashes as soon as it tries to check for new messages:

Process:               Mail [1174]
Path:                  /Applications/Mail.app/Contents/MacOS/Mail
Identifier:            com.apple.mail
Version:               8.2 (2102)
Build Info:            Mail-2102000000000000~1
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           Mail [1174]
User ID:               501

Date/Time:             2015-07-14 08:59:48.324 +0100
OS Version:            Mac OS X 10.10.4 (14E46)
Report Version:        11
Anonymous UUID:        4F6F2F84-F869-25C2-1C87-B1246982BFD7

Time Awake Since Boot: 2200 seconds

Crashed Thread:        2  Dispatch queue: MFEWSAccountRequestResponseQueue :: NSOperation 0x600000697340 (QOS: UTILITY)

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

Application Specific Information:
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Root Folder Id changed from AAMkADA5M2EyZWFiLWY1ZTctNDJlMS05MzQ1LTkyMDBkNTY2ZWEyMQAuAAAAAAA87sBtlAlTTJOPv8b7pvr6AQAUpHXDFMbMR5FSnLwG4BOUAAAAiMo7AAA= to AAMkADM0MjZkNGU4LTcwZGUtNDZhYi1hNjg4LTk0MGI5NWM4NzU3MgAuAAAAAAAcQlpkIwGwSb0hc5q+A04eAQB+EaxIvJoGTJt2RsDw05zJAAAAlpk5AAA=: once an account is created, the root folder id shouldn't change on the server'
abort() called
terminating with uncaught exception of type NSException

What's my best course of action? I have tried removing the 'Envelope' index files and rebuilding but with the same result. I don't want to completely wipe everything unless I absolutely have to, as I don't want to lose my local cache of messages (especially as they are no longer available on the server).

  • hopefully you have archived mails, if so delete the email account. now make a new one (or recreate the old one). based on this message "once an account is created, the root folder id shouldn't change on the server'"
    – Ruskes
    Jul 14, 2015 at 8:15

2 Answers 2


Buscar has the gist correct, though I would add a step: backup your ~/Library/Mail folder (OPTION-Drag it to the desktop) then delete the account.

One that is done add it back. If your old mail has vanished when the new account has been established just import the backed up mailboxes sitting on the Desktop.

  • Thought there may have been a more imaginative solution but this was what I ended up doing - unfortunately importing .mbox files back on to Exchange loses the original sent/received date and time. Something to look out for if this is particularly important to anyone.
    – James
    Jul 15, 2015 at 9:25

I used a more radical approach, because all my mail accounts (those not using Exchange) were using the IMAP protocol. I didn't backup my ~/Library/Mail folder. I just moved it out elsewhere completely, then disabled the Exchange mail account inside System Prefs, and finally relaunched Mail.app. The app now re-downloads all mails...

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