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Well, no. I upload different worlds every couple of days and I don't ever download the world.
Sorry I took so long to reply, I'e been busy..... 
For the mean time, I just keep uploading the world until it works. It may take a while, but it's the only way I have.
+Roman I got the same error...... Fatal Error on uploading! (Can't unpack archive)
I was using Microsoft Edge and I guess since that's a new browser it still has some things it needs so I tried using Google Chrome and it worked.
Ugh! The problem happened again.......
Roman - No. I don't think so.....
tobsxdlol - Thanks for the tip I'll try it out.
FaZeDarkStar - Alright I try it. Appreciate your help!
FaZeDarkStar I tried another browser and it work. Hopefully, I won't run into this problem again. But anyway, thanks for everyone who helped!! 
It isn't very big, at all in fact. It's just a survival world with some buildings. To be exact, the zip file size is 8.43 MB
I've just recently joined Aternos and I have enjoyed the service it provides, however I have been receiving issues when it comes to uploading a world. I chose the world which was packed in a zip folder, then I pressed the Upload world button. After a while, the page either fails to load or it goes to captcha. Then, I reload the page, or complete the captcha and I received a message at the bottom right-corner of the page that says something on the lines of "Fatal Error When Uploading: Can't unpack archive" If anyone out there can give me a tip or some help, please leave a message. 
