Object layout 'delete' not found

There is a page on my page list that actually doesnt exist. When a click to delete it, I get the message: Object layout 'delete' not found, in the web. In Admin I get a page saying "This page will not exist until it is saved. - # Error 404 - Woops! Looks like this page doesn't exist.". Any ideas? Thank you.

@edbr, Please help the community help you by providing succinct and accurate information that makes the context of the issue perfectly clear.

Preferably, you provide a step-by-step description of:

• What you did
• What you do
• Where you do it?
• And what response you get.

There is a page on my page list that actually doesnt exist.

• What is "my page list"? Is this a blog list? Or the list of pages in Admin?
• It is not a habit of Grav, nor Admin, to show non-existing pages.
  • Did it ever exist?
  • How did the page got deleted?

When a click to delete it, I get the message: Object layout ‘delete’ not found, in the web.

• Where do you click to delete it?
• What do you mean by getting a message "in the web"?

In Admin I get a page saying “This page will not exist until it is saved. - # Error 404 - Woops! Looks like this page doesn’t exist.”.

• Does this mean everything mentioned earlier was not in Admin?
• What did you do before you got this message?

And I have now this error. I added a post into blog and click on save button to start add content on page. I see the page in the list. But when I try to delete/modify or view the page, I get a 404 error

Don't understand why and how it was happened