[Solved]-Why ReactHighcharts SolidGauge's rounded is not working in react-Highcharts

The problem is where you're getting the solid gauge extension from. The highcharts-solid-gauge package is massively out of date.

Use this instead

import SolidGauge from 'highcharts/modules/solid-gauge';

Version you're using (see https://npmcdn.com/highcharts-solid-gauge@latest) is v4.2.3

Where as the current version is v5.0.12 - https://code.highcharts.com/modules/solid-gauge.js

If you go to the official JSFiddle example you referenced, and change the solid-gauge script src to https://npmcdn.com/highcharts-solid-gauge@latest you'll see the same problem you're having.