This error occurs when an add-in registry key points to a VSTO solution, but the system cannot find the runtime engine. To fix this, download and run the standalone VSTO runtime installer from the official Microsoft website. Deployment Manifest Failures
: Typically, if you install a 64-bit version of Office on a 64-bit Windows OS, this runtime is installed automatically alongside it. Official Resources For documentation and downloads, you can refer to: microsoft visual studio 2010 tools for office runtime -x64-
The requirement is dictated entirely by the , not the bitness of your Windows Operating System. System Environment Scenario Appropriate Runtime Selection This error occurs when an add-in registry key
VSTO requires Windows and desktop Office installations. Web add-ins run cross-platform on Windows, Mac, iPad, and web browsers. Official Resources For documentation and downloads, you can
Specifically designed to run Office customizations within 64-bit editions of Microsoft Office .