DevTools failed to load SourceMap: Could not load content for http://localhost:3000/main.6cba98a79fff01b3f27b.hot-update.js.map: HTTP error: status code 404, net::ERR_HTTP_RESPONSE_CODE_FAILURE code example

Example 1: 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

Example 2: DevTools failed to load SourceMap: Could not load content for http://127.0.0.1:8000/bootstrap-select.min.js.map:

You need to go into Dev Tools settings and you need to unckeck 
"Enable JavaScript source maps"
"Enable CSS source maps"