Iframe & Laravel

How can I implement this route inside the iframe?

What exactly do you mean by this? You can’t ‘implement a route inside an iframe’, that doesn’t make any sense. You implement a route in your PHP code, by adding it to your routes and making sure it returns some sort of view. You can load a specific page (or indeed a route) in an iframe, but you can’t implement it in an iframe.

Also, the URL you have in your iframe (probably) isn’t a Laravel route, just a regular PHP file. You don’t need Laravel at all to open those.

If you’re getting a 404, that’s presumably because the file in question doesn’t exist. One reason why it might not exist would be because you wrote the URL wrong – and indeed, as @click says, the URL you use in your iframe’s src attribute is not the same URL you use in the text in your question.

So first things first: does http(s)://{your-domain}/assets/plugins/summernote/plugins/filebrowser/filemanager.php actually exist?

@click @kokoshneta Looks like you both are right. The path was wrong. Now it's loading, but I'm getting 412 Precondition Failed on the AJAX requests that are performed by the script. What might this be?