child3 returning error and not loading

[jyotiranjan222-dev]

Have taken the exact zip download
1- npm install done
2- started the container using npm start
3- started the child1 and child2 using npm run serve:single-spa
4- created a child-3 app as directed in video

but while clicking on the child2 and child3 getting the below error.-

ERROR Error: Error loading http://localhost:8080/child3.js (SystemJS Error#3 https://git.io/JvFET#3)
at HTMLScriptElement. (system.min.js:4:5949)
at e.invokeTask (zone.min.js:13:7855)
at Object.onInvokeTask (core.js:27175:1)
at e.invokeTask (zone.min.js:13:7776)
at t.runTask (zone.min.js:13:2934)
at t.invokeTask [as invoke] (zone.min.js:13:8987)
at _ (zone.min.js:44:712)
at HTMLScriptElement.m (zone.min.js:44:942)
Can you please suggest what could be the reason.

Could you please help, what could be the reason for the error and what I should do to get a solution.