So, after a day of hard work, building on my server, I wanted to download it as a backup, but when I did /dl world and stuff, when I tried using the world file provided, I couldn't because an error told me it's an invalid file. THIS ISN'T AN ERROR ON THE /DL COMMAND, IT'S EXTERNAL. I don't know how to explain things and my english might be bad so sorry if u don't understand..
So, the error here is that the worlds I got from downloading, are ALL invalid and don't work. I tried putting it in the .minecraft/saves folder, but the world didn't show up in the list..
What can I do? There's only one /dl command in my server.