migrating-mvc-bundling

name	migrating-mvc-bundling
description	Migrates ASP.NET MVC bundling and minification from System.Web.Optimization to direct script/link tags in ASP.NET Core Razor views. Use when upgrading .NET Framework MVC apps that use BundleTable.Bundles, BundleConfig.cs, ScriptBundle, StyleBundle, @Scripts.Render, or @Styles.Render. Triggers for bundling migration, removing System.Web.Optimization, converting bundle references to static file references, or modernizing script/style includes in .cshtml files.
metadata	{"traits":".NET|CSharp|VisualBasic|DotNetCore","discovery":"lazy"}

ASP.NET MVC Bundling and Minification Migration

Converts .NET Framework MVC bundling (System.Web.Optimization) to direct <script>/<link> tags pointing at static files under wwwroot/. ASP.NET Core serves static files from wwwroot/ instead of using a bundling pipeline, so every bundle reference must be replaced with explicit file references.

Workflow

Progress:
- [ ] Step 1: Inventory bundle registrations
- [ ] Step 2: Replace bundle references in Razor files
- [ ] Step 3: Remove BundleConfig and related code
- [ ] Step 4: Remove System.Web.Optimization usings
- [ ] Step 5: Verify build

Step 1: Inventory bundle registrations

Search for BundleTable.Bundles across the project. The registration is typically in a file named BundleConfig.cs but may be elsewhere. Record every bundle name and its included file paths — these are needed to expand references in Step 2.

Example registration to look for:

bundles.Add(new ScriptBundle("~/bundles/jquery").Include(
    "~/Scripts/jquery-{version}.js"));
bundles.Add(new StyleBundle("~/Content/css").Include(
    "~/Content/site.css"));

Step 2: Replace bundle references in Razor files

Search all .cshtml files for @Scripts.Render and @Styles.Render calls. Replace each call with the corresponding direct tags, using the file paths recorded in Step 1. Convert paths to be relative to wwwroot/ because ASP.NET Core's static file middleware serves from that directory.

Before:

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

After:

@section Scripts {
    <script src="~/scripts/jquery.min.js"></script>
    <script src="~/scripts/jquery.validate.min.js"></script>
}

For style bundles, use <link rel="stylesheet" href="~/css/site.css" /> instead of @Styles.Render.

Step 3: Remove BundleConfig and related code

Remove the bundle registration code found in Step 1. If the class (commonly BundleConfig) contains only bundling code, delete the entire file. Clean up all references to the removed class — check Global.asax.cs, Startup.cs, and any other files that call the registration method.

Step 4: Remove System.Web.Optimization usings

Search all .cs files for using System.Web.Optimization and remove those statements. This ensures no stale namespace references remain.

Step 5: Verify build

Build the project to confirm no compilation errors from removed references. Check for any remaining references to System.Web.Optimization or BundleTable.

Success Criteria

• No @Scripts.Render or @Styles.Render calls remain in .cshtml files
• All script/style paths are relative to wwwroot/
• No System.Web.Optimization references remain in any .cs file
• Bundle registration code and its call sites are removed
• Project builds without errors