title: How do I cancel and rollback a custom action in VS2010 Windows Installer?
body: <p>I have a custom action that adds/removes a certificate from the Trusted Root Certificates via the Windows Installer.  I achieve this by using a <a href="http://msdn.microsoft.com/en-us/library/d9k65z2d%28v=vs.80%29.aspx" rel="nofollow">CustomAction</a></p>
  
  <p>It's possible that the user may not have permissions to add the certificate to TrustedRoots, or they may select "Cancel", how do I roll back the previous actions, and tell the installer that I've cancelled the process?</p>
  
  <p>As it stands now the Windows Installer is always reporting a success response even if it fails.</p>