After the upgrade, when you write source data that contains a FileName port or when the FileName in the mapping is not excluded from the input fields of the target, the mapping runs successfully. However, it inserts an empty string in the FileName column in the target. Previously, the source data with the FileName port was written to the Microsoft Fabric Data Warehouse target.

To prevent writing empty strings, perform the following steps:

Exclude the FileName port when you create a new target at run time.
Do not use the FileName port column when you use an existing target object.
Connect FileName port values from the source to a different port.