Vagrant up - the server does not start because the problem is with the ssh library

Question

I get this errormessage:

An error has occurred in the SSH core library that Vagrant uses. The error message is shown below. In many cases, errors from this library are caused by ssh-agent problems. Try disabling your SSH agent or deleting some keys and try again.

This is my first time with a tramp.

I read this guide.

https://wpbeaches.com/setting-up-a-wordpress-vvv-vagrant-workflow/

I have Windows 10, vagrant 1.8.5, the new version of Oracle VM.

I read a lot about this problem, but nothing helps me.

Maybe someone knows a solution.