Problem
When exporting files, an error occurs when you attempt to export a file object before you export the object to which it is attached, such as when you set the export object weight to export a design file before the design document that is related to the file.
'Object reference not set to the instance of an object'.
Solution
This issue occurs because the file exists in the database before the revision to which it should be attached. Therefore, you must set the export object weighting to export a file object before exporting the file to which it is attached. For example, you must set the export object weight so that design document will be exported before the design file.
You can rearrange the export object weight in the Stage to Target Object Map using the Data Validator Administration Module. For more information on setting the export object weightings,
see Define stage object to target object mappings.