DevTools failed to load SourceMap: Could not load content for http://localhost:3000/main.729c40ca701f2f46ad94.hot-update.js.map: code example

Example: DevTools failed to load SourceMap: Could not load content for

Open Developer Tools, 
go to "Settings" for Developer Tools, 
then uncheck Enable JavaScript Sourcemaps under the "Sources" settings.
Restart Browser if needed