Error: MigrationPermanentException: Active Directory property ’homeMDB’ is not writeable on the recipient for a particular mailbox could be one of the error you may face while migrating your on-premise Exchange server mailboxes to Office 365. Also, you may face this issue while moving from the old Exchange to new version internally. Recently I encountered a similar situation in the Hybrid Exchange setup with Exchange 2007 and Office 365. Surprisingly, this error appeared for specific users only.
The main reason for this error is the permission of a particular user account in the domain. The wrong or missing user permission of the particular account is stopping the Exchange command to move the mailbox from on-premise Exchange servers to Office 365 online. Here is the way to solve this error and migrate the affected user mailboxes.
We need to enable the inheritance of permission for the particular Active Directory account.
1) To enable the required security permission for the AD user, we must see the security tab in the Active Directory users list. Open Active Directory users and computers on your domain controller and change the view to Advanced Features as below.
Now you should be seeing the security tab for the users and computers objects.
2) Open the user account, which gives the error while migrating to Office 365.
Under the ‘Security’ tab (this will be visible when you enable Advanced View as mentioned in step 1), click on the ‘Advanced’ button. Mostly the inheritance permission for this user would be disabled. Enabling this permission will solve the issue, click on ‘Enable inheritance’ button and apply the changes.
3) In hybrid setup, you should sync this local AD change of user account to Office 365 through Azure AD Connect. Either you can wait for the scheduled sync or execute the delta sync manually by the following command on the server where Azure AD sync tool installed.
Start-ADSyncSyncCycle -PolicyType Delta
Once this change synchronized to Office 365, you should be able to migrate the mailbox from on-premise Exchange server to Office 365 online without Active Directory property ’homeMDB’ error.
If you are doing this setup for internal mailbox migration, with the earlier user account inheritance security changes, you should be able to do it. The Azure AD connect option is only for the hybrid Exchange server setup.