one thing I can think of is that sd cards need to have a certain ammount of free space to function properly. so if you say you have a 256gb and you only have 4gb left then that can create issues. they say you should leave at least 10% free space on sd/ssd's which in your case would be about 25gb.
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it's not ezpz when you have 250gb of games installed.
yes that would be optimal but he doesn't have that option since he didn't have a backup of his sd card.Its quite easy when you make a copy of the entire sd card to your pc. Then when things like corruption happens you can just copy it back.