I got a realms a couple of days ago. My friends and I were previously playing on a small locally hosted server.

We tried to upload the server's map to the realms by adding it to my solo saves, and then trying to upload. I always get an error (-1) when trying to upload it. It gets to 100%, and stops working after attempting to verify the files.

I have tried removing all players' data from the save, and all non-essential files (like the map icon, datapacks, advancements, and raids data).

I went ahead and checked the logs, and it always say: 

[ForkJoinPool.commonPool-worker-1/ERROR]: Caught exception while uploading:
java.net.SocketTimeoutException: Read timed out

followed by the error's details.

It might be important to note that the file is roughly 1.5GB in size, but I have read in your FAQ section that the actual limit is 5GB, so that shouldn't be an issue.

I've also given my account's password to my friends, as well as the save so they could try to upload the world themselves, but the all get the same error, except one got a (500) error.

I also tried uploading other smaller worlds, and it worked fine, which leads me to believe that there may be something I'm doing wrong?

Thanks for helping me out !