Exception: undefined, Failed to fetch


I moved my kirby file from MAMP to FTP server.
Everything works well except writing.

If I write any text, I get this error “Exception: undefined, Failed to fetch”.
It wasn’t problem in my MAMP server, but it’s problem in FTP server.
(so I think, it’s not problem about blueprint)

Does anyone know how to solve this problem?

Is there any more information in your browser console?

When exactly does the problem occur? As soon as you start entering text or when you try to save your changes?

The problem is, that I can’t write or upload anything in website.

Is this problem from hosting?
I have tried so many method to solve this problem.
but I couldn’t fix it.

Which browser are you using? Does the error also persist in other browsers? Is there any more information when you click on the arrows?