Mail upgrade fails on import

Question

Hi
When upgrading to Yosemite, the Mail app has gone into an endless loop of importing.
It tries to import, then reports that it has failed.
You then get a message about the Mail Index has been damaged and so you have to quit Mail.
It then starts the process all over again.
I have around 31K messages.  But Mail is COMPLETELY unusable.  Cant open/view/read/send/search/play with emails.
Very disappointing...
Here are some interesting entries from the system log:
20/10/2014 10:49:34.239 Mail[3459]: resolvedBaseMailDirectory /Users/amorton/Library/Mail
20/10/2014 10:49:48.805 Mail[3459]: Capturing diagnostics to trace took 14.565747
20/10/2014 10:51:07.133 Mail[3459]: open on /Users/amorton/Library/Mail/V2-Temp.noindex/[email protected]/Personal.mbox/Info.plist: No such file or directory
20/10/2014 10:51:22.518 Mail[3459]: Exception during migration: data parameter is nil
20/10/2014 10:51:22.518 Mail[3459]: Migration (simple) failed and took 108.279527 seconds
20/10/2014 10:51:27.228 Mail[3459]: emlxCountPreMigration 61078
20/10/2014 10:51:27.228 Mail[3459]: emlxCountPostMigration 61078
20/10/2014 10:51:27.229 Mail[3459]: lostAndFoundEmlxCount 0
20/10/2014 10:51:27.229 Mail[3459]: messageCountPreMigration 31712
20/10/2014 10:51:27.229 Mail[3459]: messageCountPostMigration 31712
20/10/2014 10:51:27.230 Mail[3459]: MessageTracing took 4.710642
20/10/2014 10:51:27.230 Mail[3459]: Upgrade failed because of exception: data parameter is nil
20/10/2014 10:51:27.231 Mail[3459]: Library upgrader failed: Error Domain=MCMailErrorDomain Code=1029 "data parameter is nil" UserInfo=0x7fac01622a90 {NSLocalizedDescription=data parameter is nil}
The thing is - that file does exist (the Info.plist reported at 10:51)
Any ideas, or are we destined to wait for the upgrade patch!?
Andrew

Answer 1

For what it's worth, I solved my problem.  I went into the preferences for iCloud and unchecked mail and then rechecked it.  Mail then started up just fine.  However, my old messages for a couple pop accounts were not there (icloud and google mail were fine).  So then I tried to import, but in the dialogue box, it didn't show the mail folder or even the library folder (which is normally hidden).  So in finder, using the option + go menu I navigated to the libary folder and made an alias for the missing pop account's mail and put that on the desktop.  Then I went back to mail and selected the alias for the missing pop account mail.  It had no problem importing then, although it did take a while.  Then when I selected import again, for some reason it went right to the correct mail folder within the library folder and I didn't have to make an alias for the other account.  The mail all came in then under the imported category.  For me that's actually ok.  I had one piece of mail I really needed to find, and the search found it right away.  So at least for now, all is well.