Corrupted dbox file around offset= EOF reading msg header

Hello Dovecoters,

I am using dovecot-2.2.10-8.el7.x86_64 on RHEL 7.4

When I backup mdboxes (using SIS) using this command

doveadm -Dv -o plugin/quota= sync -1f -u user1@user.com mdbox:/mailbackup/user1

mails get backedup but all m files are not copied. Last file copied is m.4

If I run the command again I get below error

I tried with doveadm backup command as well (many times).

Error: Corrupted dbox file / mailbackup/user1/storage/m.4 (around offset=3732536): EOF reading msg header (got 0/30 bytes)

Result is all mails are not backedup. Destination is a folder on a NAS with NFS mapped to the server.

Thanks/DP

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