Check out example codes for "adminlte.min.css.map error". It will help you in understanding the concepts better.

Code Example 1

Delete /*# sourceMappingURL=bootstrap.min.css.map */ in css/bootstrap.min.css
and delete /*# sourceMappingURL=bootstrap.css.map */ in css/bootstrap.css

It is working for me.
I hope it will work for you also.
Namaste _/\_

Code Example 2

Source map files, like bootstrap.min.css.map, are generated automatically during files minification/compiling process. They actually are not needed for the production, but at the same time occupy 3 times more disk space than ones which they are mapping.
If you want just to remove that message, you can either remove comments like /*# sourceMappingURL=bootstrap.min.css.map */ in bootstrap.min.css, bootstrap.min.js, popper.min.js or any other ccs file in which you are getting error.

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