we are currently migrating from Exchange 2010 to Zimbra Network Edition 8.0.6 on Centos 6.5 64-bit.

We use command line migration tool to migrate all users' mailbox content (except spam). This includes also calendar appointments.

In testing there was no problem but in the real migration, we have encounter a several types of errors which lead to several appointments not being migrated.

The first one very common error is (appointment subject is "Get Ready for HP Converged Systems"):
Error on appointment Get Ready for HP Converged Systems -- system failure: writing invite to calendar item table: UID=040000008200E00074C5B7101A82E00800000000000000000000000000000000000000007E0000007643616C2D55696401000000303430303030303038323030453030303734433542373130314138324530303830303030303030304530444239463936373436444335303130303030303030303030303030303030313030203030303030353645363237463639413835433934424131303942353938374546454535393600
Another one is (appointment subject is "Priprava PPT na zalohovani" and "Cesta obsahuje neplatn├ę znaky" means in czech something like "The path contains invalid characters"):
Priprava PPT na zalohovani exception caught in ProcessItems->api.AddAppointment Cesta obsahuje neplatn├ę znaky.
And the last one is (God knows if this is related to any lost item at all, logs are quite a mystery):
CSmigrationwrapper MAPI edgecase MAPI Could not be returning all the items for the folder - Migration is not complete.Please re-run migration for the user
The two mentioned appointments as well the XML file used for command line migration tool can be downloaded here.

Also both the appointments can be easily imported vie zimbra web client so why the migration tool failed?

Any help is appreciated.