Null pointer exception often means that some required object or value is not available. At first glance it looks like the file object does not exist. Best way to find this out would be to add a breakpoint to the microflow and run the action again. If you go through it step by step, you might see what is wrong. (eg retrieve did not give a result).
You can add an additional check if the file exists before trying to download it and debug the logic to find the root cause.
Hello Micha Friede,
Thank you for your quick response.
A mapping of an attribute was missing in the export template.
It's mapped now and i'm able to export.
Best Regards,
Karuna