I'm trying to install a very simple Excel VSTO Addin (just one dll) using the WIX installer method, making sure that the "Are you sure you want to install this customization?" prompt does not show at all.

  1. I've imported the certificate and exported again as a PFX without the chained informations

  2. I've signed everything I could using following post-build events:

- "signtool.exe" sign /f $(SolutionDir)Thawte.pfx /p myPwd$(TargetPath)

- "mage.exe" -sign $(TargetPath).manifest -CertFile $(SolutionDir)Thawte.pfx -Password myPwd

- "mage.exe" -sign $(TargetDir)$(TargetName).vsto -CertFile $(SolutionDir)Thawte.pfx -Password myPwd

3. I installed the Thawte.pfx certificate on the Local Machine, in the Trusted Root Certification Authorities

1 Answers


The prompt comes from VSTO - it stores the list of approved addins in HKCU\Software\Microsoft\VSTO\Security\Inclusion - if your addin is not there, you can create a registry key there listing our addin. The PublicKey value can be extracted from your .vsto file.