Warning Item 'AQMkAGI3MmUAAQfvQwAAAA==' Isn't Deleted. Result = 'Error'. ErrorCode = 'ErrorNonExistentMailbox' or Warning Item 'AAMkA=' isn't deleted. Result = 'Error'. ErrorCode = 'ErrorAccessDenied'. (4233461)

When synchronizing a mailbox to Office 365 or Exchange 2013 or Exchange 2016 (with MMEX 8.13 only), the mailbox has been processed in a sync collection for days and the progress hasn't moved.  Upon reviewing of the Migration Agent for Exchange (MAGE) log file one of the two following messages is displayed.

Warning   Item 'AQMkAGI3MmUyMTdiLWIyNTItNGU1OC1iYzRiLWMwYmVkMmNkNGEyNgBGAAADr8==' isn't deleted. Result = 'Error'. ErrorCode = 'ErrorNonExistentMailbox', or 

Warning  Item 'AAMkAGQxY2M5NDRlLTQ0N2QtNGU4Mi05ZDlmLTk0OTNkNmQwZjQxNABGAAAAAA=' isn't deleted. Result = 'Error'. ErrorCode = 'ErrorAccessDenied' or

Warning Item 'AAMkADlkZTJlNzdmLTY1OWYtNGVhYS04YjljLTdkM2I2YjZlZGMzMABGAAAAAAByR+2uPf3iQ4i+4m7qb+DtBwDRh8R2zoSyQ5ltlyI0m7SbAAAAAAEMAADRh8R2zoSyQ5ltlyI0m7SbAACXm5QfAAA=' isn't deleted. Result = 'Error'. ErrorCode = 'ErrorCannotDeleteObject'.

Warning Item 'AAMkAGUxODIyOTA4LWZiYTAtNGZiMi05OTgxLTAwYTIxOTBmMjY3MABGAAAAAAChrpal5kmTTLZ+mSH+BOgdBwBccQ/t78bMT5j5SIhHATnEAAAAABfvAABccQ/t78bMT5j5SIhHATnEAABGXAwcAAA=' isn't deleted. Result = 'Error'. ErrorCode = 'ErrorInternalServerError'.

This can happen if target Office 365 mailbox was deleted and recreated or target Exchange 2013 or Exchange 2016 mailbox was disabled instead of using KB 153020 (at https://support.quest.com/migration-manager-for-exchange/kb/153020) to remove the contents but leave the target mailbox in place.

To resolve the issue, please do the following:

1) Create a new disabled mailbox or calendar collection and add problem mailbox(es) to it.

2) For the newly created collection enable parameter ClearAllSyncDataOnResync with MMEX PowerShell cmdlet.

For example:

Set-MMExCollection –Name MailCollectionName –Type Mail –ClearAllSyncDataOnResync $true

Please refer to https://support.quest.com/technical-documents/migration-manager-for-exchange/8.14/user-guide/22#TOPIC-711685 for details on enabling Migration Manager parameters with PowerShell.

3) Enable mailbox or calendar collection and resynchronize problem mailbox(es).

4) As soon as the resynchronization is completed disable parameter ClearAllSyncDataOnResync set at point 3) with MMEX PowerShell cmdlet. 

For example:

Set-MMExCollection –Name MailCollectionName –Type Mail –ClearAllSyncDataOnResync $false

Note: If a mailbox is added to both mailbox and calendar collection, you don't need to resynchronize both collections. Resynchronizing in only mailbox or only calendar collection is sufficient to resolve the issue.