Installing/Upgrading .NET Before Installing IIS – Windows Problem

Target Audience: IT Manager
Article #: 13625


When setting up web services on a Windows computer, it is critical to make sure any .NET installations or upgrades get done FIRST. If .NET is upgraded or installed after IIS is installed, there is risk that IIS will not work correctly. Although repairs can be done, often the user’s best approach is to uninstall the critical .NET components, install IIS, and the reinstall .NET again. For best results it is always best to install .NET before IIS.

Situation and Symptoms

  • Installation of new software requires both install of IIS and install or upgrade of .NET.
  • Problems with IIS cause the software to fail immediately after installation.


There are two known cases where this has caused issues.

Example 1: BreadCrumbs HTTP Error 500.19 – Internal Server Error

Example 2: TEKLYNX CENTRAL “Warning IIS is Not Configured Properly”

It appears that .NET, when installed or upgraded, will only install IIS components such as dll files and update config files properly if IIS is already installed on the server. That makes some sense as why should it install components to something that is not being used or even installed? Since, in these situations, IIS was installed after .NET was upgraded, those components were missing and config files were not updated.


To resolve the situation the user should, if possible:

  • Run repair on the .NET installation.
  • Uninstall/reinstall the critical .NET components.

If possible, the user can try to identify the missing components, such as dll files and replace them along with updating the critical config files manually. However, this requires extensive knowledge of what is missing and where/how to update the config files. Also, the risk remains that missing files and config entries still exist. Those missing elements may pop up at a later (and likely less convenient) time.

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