The thing is that I'm only getting this problem in Poweramp. As I mentioned in my post, other music players are having no problem reading the music on my SD card, only Poweramp after this last update. And the other reason I know it's not my SD card is that one of my music folders was not on the SD card, but on the smartphone's storage, and I received the same error message when trying to read music from it. My other music app is 'Player Pro', so right now, I'm using it because I'm not having this issue with Player Pro. I really like Poweramp, but right now, with the problems caused by recent updates, I have to say that I'm not too happy with it.