| name | launching-iisexpress |
| description | Launch a .NET Framework ASP.NET project using IIS Express from the command line, replicating how Visual Studio would run it. Use when the user wants to start, run, or test the web app locally during migration. Do NOT use for .NET Core or modern .NET apps — use dotnet run instead. |
Launch ASP.NET Web App with IIS Express
Start an ASP.NET project (Web API, MVC, Web Forms, etc.) using IIS Express from the terminal. This skill provides a template PowerShell script and a workflow for discovering project settings, creating a launch script, and running it.
Prerequisites
- .NET Framework targeting pack installed (version matching the project's
TargetFrameworkVersion)
- IIS Express installed (ships with Visual Studio, typically at
C:\Program Files\IIS Express\iisexpress.exe)
- NuGet packages restored:
msbuild <solution-path> /t:Restore /p:RestorePackagesConfig=true
- Solution built:
msbuild <solution-path> /p:Configuration=Debug
Workflow
1. Check for an existing launch script
Look for a Start-IISExpress.ps1 (or similar) in the solution root or a scripts/ folder. If one already exists, skip to Step 4 — Run.
2. Discover project settings
Read the target project's .csproj to find:
- Site name: The project name (e.g.
MyApp.WebApi)
- Port: Look in
ProjectExtensions > VisualStudio > FlavorProperties > WebProjectProperties > IISUrl for the localhost URL and port
- Physical path: The absolute path to the project directory containing
Web.config
- Solution root: The absolute path to the folder containing the
.sln file
3. Create the launch script from template
Read the template at references/Start-IISExpress.template.ps1 (relative to this skill). Copy it to the solution root as Start-IISExpress.ps1 and replace the placeholder variables:
| Placeholder | Replace with |
|---|
{{SITE_NAME}} | The project name from step 2 |
{{SITE_PORT}} | The port number from step 2 |
{{WEB_PROJECT_PATH}} | The absolute path to the project folder |
{{SOLUTION_ROOT}} | The absolute path to the solution root |
4. Run
Build and launch:
msbuild <solution-path> /p:Configuration=Debug
.\Start-IISExpress.ps1
The script launches IIS Express as a detached process and returns immediately after confirming the site is listening.
5. Verify
The script performs a basic readiness check automatically. To further verify, use curl in the same terminal:
curl http://localhost:<port>/
Use the default route or landing page configured in the project (e.g. the IISUrl from the .csproj).
6. Stop IIS Express
.\Start-IISExpress.ps1 -Stop
Or directly:
Get-Process iisexpress -ErrorAction SilentlyContinue | Stop-Process -Force
Template
The template script is at references/Start-IISExpress.template.ps1. It handles:
- Stopping any existing IIS Express process
- Copying the IIS Express
applicationhost.config template from C:\Program Files\IIS Express\config\templates\PersonalWebServer\applicationhost.config
- Patching the default
WebSite1 site entry with the target project's name, physical path, port, and Clr4IntegratedAppPool
- Writing the config to
.vs\config\applicationhost.config relative to the solution root
- Launching IIS Express as a detached process (returns immediately)
- Polling until the site is accepting connections
Troubleshooting
- Port conflict: If the port is in use, check
.vs/config/applicationhost.config for the binding or pick a different port
- Missing packages: Run
msbuild <solution-path> /t:Restore /p:RestorePackagesConfig=true first
- Missing IIS Express: Install Visual Studio or the standalone IIS Express download
