When i renamed my index.md to main.md to and then created another index.md it said this "Error: Error: Request failed with status code 400"

so basically i moved my entire index to another page by renaming it but when i made another index so that when they visit my site they wont see readme.md message. but it just gave me the error in the title.
my github reposito link is https://github.com/NikoNiyazi/nikoniyazi.github.io
sorry if i didnt really explain what my problem is

what error is that ?

this is what I’m seeing on my end

it seems working