URL Not Found - deployment was successful

I’m having the same problem with another user (404 URL not found), however the answer to his problem was given privately. Could you tell me how I can resolve this same type of problem?
The deployment was successful but when loading the website, I am encountering this error

https://bugingar.onrender.com/

Hi,

The response on https://bugingar.onrender.com/ is not a Render error. It’s your app showing that a root path wasn’t found for some reason. You’ll need to check your code defines a root path, or maybe you have other paths defined?

Alan