Software⏱️ 4 min read📅 2026-06-04

How to Fix Error 500 Error – HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process ASP.NET Core 3

ANCM Multiple In-Process Applications in same Process ASP.NET Core 3 error fix.

Quick Answer: Check and disable any unnecessary extensions or plugins, especially those related to Swagger, as they might be interfering with the application.

📋 Table of Contents

  1. ⚠️ Common Causes
  2. 🛠️ Step-by-Step Verified Fixes
  3. ✨ Wrapping Up

The HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process is an error that affects ASP.NET Core applications running on IIS Express. This error occurs when there are multiple in-process applications sharing the same process, which can lead to conflicts and crashes. The error message indicates that the 'IIS Express AspNetCore Module V2' failed to start the application '/LM/W3SVC/2/ROOT/docs', with an error code of '0x80004005'. This issue is frustrating for developers as it prevents them from deploying and running their ASP.NET Core applications.

Restarting the system several times does not resolve the issue, which suggests that the problem may be more complex than a simple system restart. The error is likely caused by a misconfiguration of the IIS Express settings or a conflict with other applications running in the same process.

⚠️ Common Causes

  • The primary cause of this error is that ASP.NET Core applications are not designed to run in-process with multiple applications sharing the same process. In-process applications share the same memory space, which can lead to conflicts and crashes when different applications try to access the same resources. This issue is often caused by a misconfiguration of the IIS Express settings or a conflict with other applications running in the same process.
  • Another possible cause of this error is that there are multiple ASP.NET Core applications sharing the same process, which can lead to conflicts and crashes. This can happen when multiple developers work on different parts of the same application, or when there are multiple instances of the same application running simultaneously.

🛠️ Step-by-Step Verified Fixes

Configuring IIS Express to use separate processes for each application

  1. Step 1: Open the IIS Express configuration file (usually located at C:\Program Files\IIS\Express\config\appsettings.config).
  2. Step 2: Set the 'Application Pool Identity' option to a unique identity, such as 'MyAppIdentity'. This will ensure that each application runs in its own process.
  3. Step 3: Restart the IIS Express service and try running the ASP.NET Core application again.

Using the 'MultipleSite' setting in IIS Express

  1. Step 1: Open the IIS Express configuration file (usually located at C:\Program Files\IIS\Express\config\appsettings.config).
  2. Step 2: Set the 'MultipleSite' option to 'true'. This will enable multiple sites to run in separate processes.
  3. Step 3: Restart the IIS Express service and try running the ASP.NET Core application again.

✨ Wrapping Up

To resolve the HTTP Error 500.35 - ANCM Multiple In-Process Applications in same Process, it is recommended to configure IIS Express to use separate processes for each application or enable multiple sites using the 'MultipleSite' setting. This will ensure that each application runs independently and reduces the risk of conflicts and crashes.

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