The error is normal-It occurs when
1.Not formatted the pendrive correctly- Do a full format in fat32( if fat32 doesnt work, try FAT)
2.Use a different pendrive
3.Always use the first slot( the slot thats not close to BD drive)
4.This is important- Make sure there is no usb cable or any other usb devices connected to ps3 when update is happening.
5.If still same error, try upgrading (system update) by going to the recovery mode.
By the way- Why 3.50?? Why not 3.41--->Official firmware 3.55----> 3.55kmeaw( to play games from harddrive-the hack )
Afaik, these could be the possible reasons .
If these things dont work, try the 3.20 method as suggested by Markdc..thanks...aneesh
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