thank you finance71 !!!
changing the extension to lowercase, completely solved the Paypal import problem for me. No need to change anything inside the file. I also tested this with extension .CSv, and it failed.
So the code for Quickbooks' CSV import code, is requiring strict lowercase when it checks the extension. This would be a simple fix for the code team to resolve, by allowing uppercase or lowercase on the extension. They really should implement this upper/lowercase extension flexibility, because their website describes the filetypes in all caps, right on the upload page. This implies that caps are how Quickbooks refers to the file extensions, which adds to the confusion.
This -should- be an incredibly easy fix for the code. You have to specifically tell the website code which extensions are acceptable. Just duplicate the list of acceptable extensions, in caps. If they want to be fancy, they could apply a string check to extract the extension after the ".", and force it to be lowercase or uppercase. But it's not even necessary because you're only dealing with 5 acceptable extensions.
