VSTO- Unable to install this application because an application with the same identity is already installed

Question

I have an Outlook VSTO add-in I'm developing. I'm trying to test the ClickOnce deployment, but keep getting the error:

Unable to install this application because an application with the same identity is already installed.

I've manually removed the old version from Outlook's add-in menu. The add-in was also uninstalled via the add/remove programs dialog.

I've also tried the frequently suggested solution to run either of these commands:

rundll32 dfshim CleanOnlineAppCache

mage -cc

Both of these commands run fine, but they don't fix the problem. I cannot get the add-in to install no matter what I try.

Does anyone know if there are specific registry settings I could look for to try and manually delete? Or another solution?

Answer 1

Find the app folder in:

C:\Users\username\AppData\Local\Apps\2.0

and delete it.

Source: https://stackoverflow.com/a/11921554/15154

Answer 2

I've run into this before and found that there's a number of places that might be holding it.
Under HKCU\Software\Microsoft\VSTO, you will also find \Security\Inclusion\{list of GUIDs} and \Security\SolutionMetadata\{list of GUIDs}.

Check the listed GUIDs under Security\Inclusion for a Url dword that points to your vsto solution (file:///C:/Path to VSTO/yourVSTOproject.vsto) before deleting the {GUID} subkey.
Under the listed GUID keys for SolutionMetadata, find the one that lists yourVSTOproject by name.
These were two areas that I found some friction at when deploying solutions to an isolated testing machine.

On my development machine, the answer provided by John Fouhy (above) resolved the problem where rundll dfshim CleanOnlineAppCache and scrubbing the registry failed.

Answer 3

Delete the key from registry and try to install again

HKEY_CURRENT_USER\Software\Microsoft\VSTA\Solutions\{GUID}

Please verify product name DWORD value before you delete