Outlook Addin Error: Not loaded. A runtime error occurred during loading of COM add-in

Question

I have created an VSTO Outlook addin. The configuration is as follows:

• Visual Studio 2008
• Office 2007 Outlook add in (3.5 Framework)
• MSI created using Visual Studio Setup Project
• Deployed to Office 2010 under windows 7

It works fine on the Dev PC however it fails to load once installed on the test machine. The outlook addin window shows a "Not loaded. A runtime error occurred during loading of COM add-in"

It is my understanding that I should not need to install any PIA as the Office 2007 PIA are part of Office 2010.

So far I have tried the following:

• set VSTO_SUPPRESSDISPLAYALERTS however it does not show any messages when it tries to start.
• configured Fuslogvw.exe (Assembly Binding Log Viewer) however it is not showing any binding errors.
• set VTSO_LOGALERTS and it is logging all alerts however as none are shown this has not helped.

Is there anything I am doing wrong or need to do in addition to make this work?

Answer 1

Make sure you have the VSTO 3.0 Runtime installed on the test machine.

You will also need to install the VSTO 3.0 Runtime Service Pack 1 if you are running Visual Studio 2008 Service Pack 1.

VSTO 4.0 Runtime is not required in your situation because it is used with add-ins created with Visual Studio 2010. Please note that the version of VSTO and runtime generally must agree with the version of Visual Studio used to create the add-in.