World not uploading

I can't upload a map called Find the Button Nightmare, I wanted to play this with my friend but I get an error saying 103. The file is not larger than 1 Gigabyte or 50 megabytes, its around 6 megabytes. I also made sure there is no MCEDIT. Please help!! (Edit) Ok so I tried this on a new server, and it worked!! I still wanna ask the question though about why it didn't work on my other server. Explain please.

It won't let me send a screenshot, it only says the server encountered an unresolvable problem.

Edit: wait nvm now I see it after posting this.

It fixed, thank you very much!