- Rename the VSTOInstaller.exe.config file
- In Windows Explorer, navigate to the VSTO 10.0 folder
- The path is indicated in the error message and should be similar to either of
- C:\Program Files (x86)\Common Files\Microsoft shared\VSTO\10.0
- C:\Program Files\Common Files\Microsoft shared\VSTO\10.0
- In that folder, you should find a file named VSTOInstaller.exe.config. Rename it to VSTOInstaller.exe.config.old
- Ignore the warning from Windows about the file becoming unusable.
- Install the Delivery Trust Outlook Plugin setup file again (setup.exe)
We have seen this error when users upgrade from one version of Outlook to a new one (example: from Office 2010 to Outlook 2013). Outlook does not remove the older version and the component that installs the plug-ins and is trying to run the wrong version of VSTOInstaller.
Example of Error Message