How can i fix this?

This happens if you've deleted the conversations for this bot. Type /restart and let me know if it works.

Yes it works but if I try to chat with my bot clicking on the "inizia" button (first image) it doesn't work again. The problem is that a new user must click on the "inizia" button the first time that he start a conversation with my chatbot

Please point me to your bot link at onsequel.com.

Sure, here is my first episode link --> https://www.onsequel.com/channels/41191/episodes/67650/trees/67641

Please tell me tthat the problem can be solved otherwise I did all the work for nothing.

Is this happening to all users?

Now it works... i write to all my users to write the /restart command and now its all ok.

if I publish an update all my users must type /restart to see the new content or see it immediately without any command?

Yes, /restart will work.