title: ClickOnce Automatic Update error for VSTO- add-in for Excel
body: <p>I created a simple test program to try and understand how Click-Once deployment works and whether or not I can have the program automatically updated.</p>
  
  <p>It is an excel add-in with a button in the ribbon that outputs some message box. I have the deployment location set to a public location on the network and updates set to check every time the customization runs. Great - I install the add-in, open Excel, it works fine. Now I go into visual studio and update and re-publish the add-in. Now when I open Excel I get an error that says an earlier version of this application is installed and cannot install the new one.</p>
  
  <p>What do I need to do in order to get this to work? I see in the properties I can have a Pre-build event command line... so I am assuming maybe I need some sort of command line function to uninstall the old version before installing the new one? Not really sure how to go about doing this.</p>