Error while migrating mailbox with 'doveadm sync'

[Zhang Huangbin]

Dear all,

I successfully migrated hundreds of mailboxes with Dovecot 2.2.24 on OpenBSD
6.0 (amd64. Old server is OpenBSD 5.1, i386, Dovecot-2.0.17), but got error while
migrating 3 mailboxes:

# doveadm -o mail_fsync=never sync -1 -R -s '' -u user at domain.com imapc:
dsync(user at domain.com): Panic: file mailbox-alias-plugin.c: line 77 (mailbox_symlink_exists): assertion failed: (ret > 0)
Abort trap

Same error while running ‘doveadm … backup …'.
What does this error actually mean? How can i fix it?

- Here’s full log running doveadm with ‘-D’ option: http://pastebin.com/Um5fbuNM
- ‘dovecot -n’ on old server: http://pastebin.com/4E6xzFKU
- ‘dovecot -n’ on new server: http://pastebin.com/4uHwQnMN

I checked release notes of Dovecot 2.2.25/26/27, there’re 3 fixes related to
'doveadm sync’, but not sure whether it helps fix this issue.

2.2.26:
+ doveadm sync/backup: Added -I <max size> parameter to skip too large mails.
+ doveadm sync/backup: Fixed -t parameter and added -e for "end date”.

2.2.27:
- doveadm sync -1: Fixed handling mailbox GUID conflicts.