When bundling/minification is enabled, some of my bundles seem to have an invalid URL in the browser (ending with a /), and IIS gives a 403 forbidden error, as if trying to list a folder's contents.
There's no difference in the way my bundles are set up - they are not .min.css, access permissions are correct etc.
My bundles were registered as paths which corresponded to an actual folder on the solution, e.g. ~/Content/forum.
This works fine when bundling is turned off (the bundle is included correctly!), but not when bundling is enabled.
The solution is to change the registered name of the bundle to not be the same as anything that exists in the file system.
In my case bundle was specified as a directory @Scripts.Render("~/scripts") so IIS did not know how to serve the actual js file, I changed the bundle name to represent a javascript file @Scripts.Render("~/scripts.js") and that fixed it. The same was true for my style bundle.
The problem is the naming convention your bundle name should be
("bundles/css")
This solved my problem.
来源：https://stackoverflow.com/questions/13673759/mvc4-style-bundle-giving-403