If you’re running a 64-bit Windows Server and using C# to automate Microsoft Word via Interop, you may encounter a frustrating null reference error on the following line:

var appWord = new Microsoft.Office.Interop.Word.Application(); 
var wordDocument = appWord.Documents.Open(inputFile); // Fails here

This error happens because Microsoft Word Interop expects a “Desktop” folder within the system profile directory, which isn’t created by default on 64-bit Windows Server installations.

The Solution

To resolve this error, manually create a “Desktop” folder in the following location:

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C:\Windows\SysWOW64\config\systemprofile\Desktop

Here’s how to do it:

1. Open File Explorer and navigate to C:\Windows\SysWOW64\config\systemprofile\.
2. Right-click and create a new folder called Desktop.

After this, try running your code again. This simple fix should resolve the null reference error, allowing your Word Interop automation to work as expected on 64-bit Windows Server environments.