Fix: Angular CLI Timeout Error in ASP.NET Core MVC

Category: ASP.NET Core · Angular · Web Development

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The Problem

If you're running an ASP.NET Core MVC project with Angular, you may have encountered this frustrating error during startup:

TimeoutException: The Angular CLI process did not start listening
for requests within the timeout period of 0 seconds. Check the log
output for error information.

Microsoft.AspNetCore.SpaServices.Extensions.Util.TaskTimeoutExtensions
.WithTimeout<T>(Task<T> task, TimeSpan timeoutDelay, string message)

This error usually appears when the Angular CLI takes longer to compile than the default timeout allows — especially on slower machines or large projects.

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Why Does This Happen?

When ASP.NET Core launches your Angular app via SpaServices, it waits for the Angular CLI to start and listen on a port. If the CLI doesn't respond in time, the app throws a TimeoutException.

The default timeout is often too short (sometimes even 0 seconds), which causes it to fail before Angular even finishes compiling.

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The Fix — Increase the Timeout

Open your launchSettings.json file (found under the Properties folder) and add or update the "readyTimeout" property inside iisSettings:

"iisSettings": {
  "windowsAuthentication": false,
  "anonymousAuthentication": true,
  "readyTimeout": 60000,
  "iisExpress": {
    "applicationUrl": "http://localhost:16098",
    "sslPort": 44332
  }
}

Setting "readyTimeout": 60000 gives Angular 60 seconds to start — enough time for most projects to compile successfully.

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Quick Summary

Setting	Value
File	Properties/launchSettings.json
Property	readyTimeout
Recommended Value	60000 (60 seconds)

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Still Not Working?

If the error persists even after increasing the timeout, try these additional steps:

• Run npm install inside your Angular project folder to ensure all packages are installed
• Delete node_modules and run npm install again (clean install)
• Check the Angular CLI logs in the Output window for more specific errors
• Make sure your Angular CLI version is compatible with your project

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