Json file cannot be served

If I make a request to get items.json file, server returns

The resource you are looking for has been removed, had its name changed, or is temporarily unavailable.

You can check it here.

I can access it with php with readfile or fopen, so it IS on the server.

I noticed that the server specifically behaves this way with json files
while serves txt or js files without any problem.

If someone knows what’s the problem, please let me know.

You should register json mime type in your web.config file:

        <remove fileExtension=".json" />
        <mimeMap fileExtension=".json" mimeType="application/json" />

you can look at Cannot download .json files

good luck.