[GoogleDriveImporter] [Error] firstname.lastname@example.org]
 Unexpected exception processing import. Message is: Following address replacement,
new owner email address email@example.com for item [itemID+title] does not
exist in the destination domain, or does not have Drive enabled. Please check
you have provided the correct address replacements for all email addresses, including
aliases. You could use the option 'Allow Alternate Item Ownership', but this
will result in a change of ownership. cloud.solutions.Migration.Google.GoogleImporterException
When migrating Google Drive to Google Drive, unowned items in the migrating users' My Drive may be migrated. As mentioned in the linked article, it is advised that you provision all users prior to migration. If this is not done, it will result in the above error above.
It is literal in nature and means that while firstname.lastname@example.org,it came across an item owned by a user calledownerin the source. That user does not exist email@example.com the destination - i.e has not been provisioned or does exist and does not have Drive enabled, so CloudM Migrate now needs to know what to do with the item.
It gives you two options: