DevTools failed to load SourceMap: Could not load content for http://localhost/44.js.map: Connection error: net::ERR_CONNECTION_REFUSED 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"