Depends on the size of the map I suppose Loly. I have an NA 1490 with a damaged USB socket. It cannot be connected in MSM to update AU maps. It happily accepts a map update from microSD to overwrite the existing AU map loaded in .System as gmapprom1.img every time without error. The map is ~230MB. I suppose maybe you were trying to update EU which is around 10 times that size. The other point is which unit were you using? I've found older units 200/300/600 seem to have limitations using SD commands. For instance 300/600 can only write about 27 commands at a time for region backup and will hang if the 27th one isn't 'reboot' so it has to be done in batches whereas modern units will write thru to rgn255. Perhaps older units have limited 'stamina' in copying from the card as well as writing to it?