As per http://wiki2.dovecot.org/Migration/Dsync, I'm running the following command on a local dovecot server to replicate email for a single user from a remote IMAP server:

doveadm -D
-o imapc_host=remote.imap.server
-o imapc_user=gcr
-o imapc_password=XXXXXXXX
-o imapc_list_prefix=IMAP
-o imapc_features="rfc822.size fetch-headers"
-o mail_prefetch_count=20
-o mail_fsync=never
backup -R -u gcr imapc:

This runs fine for a while and successfully copies quite a lot of mail, but always aborts before completion with the following error:

dsync(gcr): Panic: file mail-transaction-log.c: line 271 (mail_transaction_log_rotate): assertion failed: (file->locked)

The exit code is 262. Does anyone know why this might happen or how to fix it?

-- Greg Rivers