Solved this E-8307 issue for me

Hello,

I also had this problem that all my USB-Sticks did not work and the XDJ-R1 showed E-8307, although I formated the sticks properly with FAT32 - they all were working on my PC and Mac. The problem for me was the partition schema. MacOS formats sticks in FAT32 with the partition schema "GUID", but you need an "Master Boot Record" schema. Reformating under Windows does not solve the problem, you really have to change that schema. You can do this by DiskPartitioningTool in detailed View under HighSierra and Mojave, you only have to partitionize the stick. I don´t know the englisch expression of the "Datenträgerverwaltung" under Windows, there you can change the schema the windows way... Hope this helps anybody.

Regards, Dom