title: Wix - MSI Upgrade without removing older version
body: <p>I would like to know if there is any way I can overwrite the old files using a newer version of the product. There are a few hundred files, so is there a better way to do this? As the upgrade is completely wiping out all files. I would like the upgrade MSI to overwrite the files.</p>
  
  <p>My upgrade logic is as follows:</p>
  
  <pre><code>&lt;Upgrade Id="$(var.UpgradeCode)"&gt;
        &lt;UpgradeVersion Minimum="$(var.ProductVersion)"
                        IncludeMinimum="no"
                        OnlyDetect="yes"                        
                        Property="NEWPRODUCTFOUND" /&gt;
        &lt;UpgradeVersion Minimum="$(var.RTMProductVersion)"
                        IncludeMinimum="yes"
                        Maximum="$(var.ProductVersion)"
                        IncludeMaximum="no"                         
                        Property="UPGRADEFOUND" /&gt;
  &lt;/Upgrade&gt;
  
  &lt;CustomAction Id="PreventDowngrading" Error="Newer version already installed" /&gt;
  
  &lt;InstallUISequence&gt;
    &lt;Custom Action="PreventDowngrading" After="FindRelatedProducts"&gt;NEWPRODUCTFOUND&lt;/Custom&gt;
  &lt;/InstallUISequence&gt;
  
  &lt;InstallExecuteSequence&gt;
    &lt;Custom Action="PreventDowngrading" After="FindRelatedProducts"&gt;NEWPRODUCTFOUND&lt;/Custom&gt;
    &lt;RemoveExistingProducts After="InstallFinalize" /&gt;      
    &lt;InstallExecute After="RemoveExistingProducts"  /&gt;
  &lt;/InstallExecuteSequence&gt;
  </code></pre>