Unable to open Mail in macOS Catalina

Question

On a MacBook Pro running macOS Catalina Version 10.15.5, every time I try to open Mail.app in one of our user's acounts, the application fails to open and I get this error:

Mail quit unexpectedly.

Click Reopen to open the application again. Click Report to see more detailed information and send a report to Apple.

Here's an excerpt from the report:

Process:               Mail [6567]
Path:                  /System/Applications/Mail.app/Contents/MacOS/Mail
Identifier:            com.apple.mail
Version:               13.4 (3608.80.23.2.2)
Build Info:            Mail-3608080023002002~43
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           Mail [6567]
User ID:               501

Date/Time:             2020-06-07 14:21:25.799 -0500
OS Version:            Mac OS X 10.15.5 (19F101)
Report Version:        12
Bridge OS Version:     4.5 (17P5300)
Anonymous UUID:        8BA95E6B-F4C0-FE35-590C-A4B6D79839C8

Sleep/Wake UUID:       560A8417-0826-4C98-BA6E-B997106BA321

Time Awake Since Boot: 56000 seconds
Time Since Wake:       1700 seconds

System Integrity Protection: enabled

Crashed Thread:        4  -[MFPersistenceVersionUpgrader run]  Dispatch queue: NSOperationQueue 0x7fe445c11cb0 (QOS: UNSPECIFIED)

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

Application Specific Information:
dyld3 mode
*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'V3->V4 migrator must be run before persistence version can be migrated to V5'
terminating with uncaught exception of type NSException
abort() called

Here's what I've tried so far:

• Restarted the computer… repeatedly.
• Tried opening Mail.app in the affected user after a Safe Boot.
• Reset the PRAM.
• Freshly installed macOS.
• Confirmed that Mail.app is in the Applications folder and tried to open it directly from there.
• Deleted all accounts from System Preferences (can't open Mail, so can't delete from in there).

All of the above has had precisely zero change on the behavior.

I created a new user on the same machine and Mail.app opens just fine on that user, so that would seem to point to an issue specific to this user, but I'm at a loss as to what that might be.

Any idea how to resolve this?

Answer 1

When I was 99% drafting the question above, I came upon a solution adapted from this post on AppleToolBox.

Here are the steps:

1. Go to ~/Library/Containers/com.apple.mail/Data/Library/Saved Application State and delete com.apple.mail.savedState.
2. Go to ~/Library/Containers and drag com.apple.mail and com.apple.MailServiceAgent to your desktop.
3. Go to ~/Library/Mail/ and drag everything in that folder to your desktop.
4. Restart.
5. If it's now working, trash everything on your desktop.

Because I had already tried deleting accounts before finding this solution, I had to re-add all of them to the user, but it otherwise seems to be working normally again.