I have the same problem as this user in his last post:
Re: Kopano Backup problems

I’m running a backup script with the following command:

kopano-backup -u <user> --recursive -O /path/to/backup/destination/

and get these output:

2017-05-24 11:50:19,710 - backup - INFO - starting backup
Wed May 24 11:50:19 2017: [error  ] M4LMAPISession::OpenMsgStore() UnWrapStoreEntryID failed 80040107: invalid entry
2017-05-24 11:50:19,750 - backup - INFO - queued 1 store(s) for parallel backup (1 processes)
2017-05-24 11:50:19,753 - backup0 - ERROR - Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/kopano/__init__.py", line 4215, in log_exc
    try: yield
  File "/usr/lib/python2.7/dist-packages/kopano_backup/__init__.py", line 76, in main
    store = server.store(entryid=store_entryid)
  File "/usr/lib/python2.7/dist-packages/kopano/__init__.py", line 1092, in store
    return Store(guid=guid, entryid=entryid, server=self)
  File "/usr/lib/python2.7/dist-packages/kopano/__init__.py", line 1454, in __init__
    mapiobj = self.server._store2(entryid)
  File "/usr/lib/python2.7/dist-packages/kopano/__init__.py", line 1062, in _store2
    self._store_cache[storeid] = self.mapisession.OpenMsgStore(0, storeid, IID_IMsgStore, MDB_WRITE)
  File "/usr/lib/python2.7/dist-packages/MAPICore.py", line 1079, in OpenMsgStore
    def OpenMsgStore(self, *args): return _MAPICore.IMAPISession_OpenMsgStore(self, *args)
MAPIErrorInvalidEntryid: MAPI error 80040107 (MAPI_E_INVALID_ENTRYID)

2017-05-24 11:50:19,755 - backup - INFO - queue processed in 0.00 seconds (0 changes, ~0.00/sec, 1 errors)
2017-05-24 11:50:19,756 - backup - INFO - stopping backup

The bad thing about it, i get the exit code 0. So my script didn’t recognise if it was successful or not.

I’m running KC 8.3.0-1042 on Debian 8.8.
Maybe there is a relic from an older installation.
I found out that i have some packages from an older version installed:

ii  kopano-lang                                           all          Translations for Kopano Core components
ii  libkcservice0                                         amd64        Utility functions for Kopano Core
ii  libkcsoapclient0                                      amd64        Client-side SOAP handling component library
ii  libkcsoapserver0                                      amd64        Server-side SOAP handling component library
ii  python-kopano                                         all          High-level Python bindings for Kopano

Can you help me fix this problem?

Kind regards