Dear  Team,

I have an exchange server 2013 with 133 Mailboxes. I have done a cutover migration and only some mailboxes synced and most of then are failed with error "Transient error ObjectNotFoundException has occurred". Could you please help on this issue.

for the failing mailboxes, it might have 2 GB in size, but after migrating 700 MB or 1 GB, getting an error as follows; that means the mailbox is partially syncing.

More details.

Data migrated: 69.78 MB (73,168,269 bytes)
Migration rate: 0 B (0 bytes)
Error: MigrationMRSPermanentException: Error: The store ID provided isn't an ID of an item. --> MapiExceptionInvalidEntryId: Unable to open entry ID. (hr=0x80040107, ec=-2147221241) Diagnostic context: Lid: 22318 Lid: 19246 StoreEc: 0x80040107 Lid: 28014 Lid: 24942 StoreEc: 0x80040107

help me with quick reply

Regards

Retheesh

Hi

1. May be you have problem with FW.

Error message when you move mailboxes from an on-premises environment to Office 365: "Mailbox Move to the cloud fail with error"

2. You need to check the integrity of the mailbox, for example, moving it to another base.
3. You need to check your administrator rights on the mailbox

PS. If this does not help, then you need to contact support Office 365, and open t

Also, any specific guide/article you are following to achieve this job ?

I would suggest you to walk through Exchange server deployment assistant that is available from Microsoft team and would be a nice approach while doing cutover migration from Exchange to Office 365.

Here is another informative article that covers all the necessary aspects and explains the steps in depth : http://www.msexchange.org/articles-tutorials/office-365/exchange-online/configuring-exchange-2013-hybrid-deployment-migrating-office-365-exchange-online-part1.html

Moreover, if the issue still persist, you may also try using this automated solution (http://www.exchangemigrationtool.com/) that could be good alternative approach and get the job done without any downtime.