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.NET VSTO Add In for Excel 2007 not loading config. Issue on one machine only!

Posted by: admin May 14, 2020 Leave a comment


We have a VSTO Add in for Excel 2007. It works on all the machines in our office except for one. This happened after MS updates last week. Basically, the Add-in won’t recognize the config file, but only on that specific machine. We uninstalled/reinstalled the application, then Excel, then the updates without any success. We then did a full Win 7 reinstall, loaded Excel, then our app, and got the same issue. We now have him running our app on a VM with XP and it’s fine. No one else in the organization is having this issue. Not sure what else to do at this point since a full windows reinstall did nothing. Any help would be appreciated.


How to&Answers:


Start > Run > RegEdit > Hkey_Current_User\Software\Microsoft\Office\Excel\Addin\YourAddInName\

Edit the Manifest key, from:

Manifest=”C:\Program Files\\WordAddIn.vsto|vstolocal”


Manifest=”file:///C:\Program Files\\WordAddIn.vsto|vstolocal”

To make this work in a deployment, right click on Setup Project in Solution Explorer > click View > Registry > and edit the key.


Are there no differences in configuration (OS, software etc) between that machine and the others on which it is working? This looks like it could be related…

VSTO 4.0 SP1 will cause a VSTO Addin to not find its config file.