Update ICX 7550 gives "File name is too big"

[LudvigB]

I try to update my ICX7550 from 8.0.95d to 10.0.10a, but have run into trouble. 

I have downloaded 10010a.zip and extracted the files to a FAT32 USB-drive. This the only content on the drive. From the manual I understand that it should be sufficient remove the startup-configuration, and reboot the switch with the USB connected for the update to start. i can see in the startup report that the USB is identified, but no update is initiated. 

I have then tried to run "copy disk0 system-manifest FI10010a_Manifest.txt secondary switch-image" but i get response
"Manifest upgrade in progress....
File name is too big"

I have tried (the poor attempt) of editing the manifest and shorten the names of all files, but it has not made any difference. 

Thanks for any suggestions on how to progress with the switch upgrade! 
Regards, 
Ludvig