I'm trying my best to make a custom Kirby's Adventure .3dn. But every time I return the next day, this error pops up and all my hard work resets.

Is there a problem to fix it or do I have to wait for the next version?

Hello, could you send me the 3dn file to debug?

Which version are you using? If it's the newest version, please use an older version as the temporary solution while i'm fixing it.