When migrating mailboxes between Exchange versions using the Exchange Admin Center you may receive the error:
Nullable object must have a value.
This error will appear when you navigate to the Recipient > Migration tab and click View Details on a migration batch. In the screenshot below we are examining a migration batch named “Test Migration to Exchange 2016” which contains two users. We are attempting to move these two users from Exchange 2013 to Exchange 2016.
From this screenshot, you will notice the Status column reports both users as successfully migrated. However, the Data Migrated and Migration Rate attributes in the right-hand pane are missing values. For an executed migration batch these attributes should contain metrics. [Read more…] about Nullable object must have a value (when migrating mailboxes)