Me and a bunch of other friends hosted our server in aternos for a while, however, after wishing to convert to Minecraft Realms we found out that we could not upload our world

What we did in order to make the trip from Aternos to Realms was that I was to download the world from Aternos and upload it to Realms. The thing is, is that I get the error above when uploading/ when the game says preparing your world...

The error states

Upload Failed! (This archives contains unclosed entries)

As I post this the subscription ticks on, hopefully it won't be exhausted by the time this is addressed?