Adding Automation Add-In to the Trusted Publishers

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Adding Automation Add-In to the Trusted Publishers
John Putman

Posts: 17
Joined: 2012-12-02
I have a combination of an Excel COM Add-In and an Automation Add-In (for UDF's). The Automation Add-In is registered using the [ComRegisterFunction] attribute to mscoree.dll. It is then loaded into our AppDomain using the ExcelApp.Evaluate() process. This has worked for years.

We now have a client that has the option 'Require Applicatoion Add-Ins to be signed by Trusted Publisher' turned on. We have code in our install that ensures that the COM Add-In is correctly signed and added to the Trusted Publishers store for our users. The problem that we appear to be running into is that the Automation Add-In is not added to the Trusted Publishers, since it is registered through the COM add-in into mscoree.dll. These clients are seeing a #NAME error when trying to use the functions due to this setting.

I have tried adding a new 'COM Excel Add-In Module' so that your code handles the registration process, but it appears that the Automation Add-In that is created will simply be registered to mscoree.dll the same way and it does not appear that there would be any way to add it to the Trusted Publishers store in this case.

Is there some step we can do to get it added correctly?

By the way, this setting might account for the issue another user was seeing a few days ago in the following thread:


-John Putman
Posted 10 Mar, 2017 16:23:32 Top
Andrei Smolin

Add-in Express team

Posts: 15594
Joined: 2006-05-11
Hello John,

You can't digitally sign mscoree.dll and this means there's no solution if you use existing tools and technologies. I can suggest that we develop a project-specific loader for your Automation add-in. It will be a separate C++ project loading your Automation add-in to a separate AppDomain. It can be created in the framework of our custom development services; see

Regards from Belarus (GMT+3),

Andrei Smolin
Add-in Express Team Leader
Posted 13 Mar, 2017 05:06:23 Top