Post request returns TypeError: Failed to Fetch

Whenever I try to make a post request using fetch, the Failed to Fetch error is returned. However, if I call wikipedia it goes through.

I have tried this with so many other websites e.g http://api.worldbank.org/v2/country/all/indicator/SP.POP.TOTL

The problem here was that the URL was not secure–that is, it used HTTP instead of HTTPS.

Identified in the following post: Hey guys I need your help