Getting "Your server returned an error status code (>= 400)."

I need to implement a universal linking for the iOS application and for that I need to host “apple-app-site-association” file on the server with the json format contains the configuration.

I uploaded the file under “public_html” folder , and i am accessing successfully through browser

There is . website which validate your apple-app-site-association file againts the domain and it is giving me this error attached in the screenshot

Your guess is as good as mine?

You’ve not uploaded a website - does this affected the test?