Microsoft Visual Studio 2010 Tools For Office Runtime -x64- -
When we append -x64- to the runtime name, we are referring to the 64-bit native loader and shim. Here is the non-negotiable rule:
The bitness of the VSTO runtime must match the bitness of the Office installation.
The x64 version installs the following critical components in %ProgramFiles%\Microsoft Visual Studio 10.0\Visual Studio Tools for Office\PIA\ and registers shell extensions specifically for 64-bit Office processes (e.g., EXCEL.EXE running as a 64-bit process). microsoft visual studio 2010 tools for office runtime -x64-
Open any Office app (e.g., Excel) → File → Account → About Excel. Look for "64-bit" or "32-bit".
Open your VSTO project properties → Build tab → Platform target: When we append -x64- to the runtime name,
The Visual Studio Tools for Office (VSTO) runtime is a software component that allows managed code add-ins (created in C# or VB.NET) to run inside Microsoft Office applications (Excel, Word, Outlook, PowerPoint, etc.). It acts as a bridge between the .NET Framework and the Office COM interfaces.
Check in Control Panel → Programs and Features for: The bitness of the VSTO runtime must match
"Microsoft Visual Studio 2010 Tools for Office Runtime (x64)"
| Error Code | Description | Resolution |
|------------|-------------|------------|
| 0x80070643 | Fatal error during installation | Often caused by corrupted .NET Framework. Repair .NET 4.x using ndp48-setup /repair. |
| 0x80070005 | Access denied | Ensure the installer is run as Administrator. On x64, Group Policy may restrict writing to C:\Program Files. |
| 0x800713ec | Microsoft Office not detected (when PIAs install) | The x64 installer can still install the runtime without Office, but add-ins will not function until Office x64 is present. |
| 1603 | General fatal error | Check the log. Most common with x64: anti-virus blocking the loader DLL registration. |
A common point of confusion for developers deploying to x64 environments is the Target Platform setting in Visual Studio.
Historically, Microsoft Office was exclusively 32-bit. However, with the release of Office 2010, Microsoft began pushing the x64 version to allow applications like Excel to address more than the 2 GB memory limit imposed by 32-bit address spaces. This shift necessitated a corresponding shift in the runtime environment for add-ins. A 64-bit process (Office) cannot load a 32-bit DLL (add-in). Consequently, the VSTO Runtime had to be compiled and provided as a native 64-bit component to bridge the gap between the Office application and the .NET Framework.