There are two possible reasons:
Check if your .map file is accessible publicly. For example, say your
https://www.example.com/js/jquery.min.jsfile has the footer//# sourceMappingURL=../map/jquery.min.mapThen check from your browser if
https://www.example.com/js/../map/jquery.min.mapis accessible.Make sure that you have a valid source map file. You can validate your map file in
https://sourcemaps.io/
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