title: Windows 10 MSI Uninstall Fails with 1721
body: <p>I have an Excel Add-in that uses a Wix (3.10) install script. The installation works fine. However, if the user tries to remove the add-in through <strong>System | Apps &amp; Features</strong>, it fails with "There is a problem with this Windows Installer package. A program required for this install to complete could not be run." Looking at the uninstall log, I see this:</p>
  
  <pre><code>Error 1721. There is a problem with this Windows Installer package. A program required for this install to complete could not be run. Contact your support personnel or package vendor. Action: _BDF865EC_34B3_4B29_986C_98D6EC1A9807, location: C:\Windows\Installer\MSI2FE4.tmp, command: /uninstall="C:\Users\Windows10\AppData\Local\myCompany\myProduct\myAddin.dll" /privileges=user 
  </code></pre>
  
  <p>The action that it is balking at is this:</p>
  
  <pre><code>&lt;CustomAction Id="_BDF865EC_34B3_4B29_986C_98D6EC1A9807" BinaryKey="adxregistrator_exe" Execute="deferred" ExeCommand='/uninstall="[TARGETDIR]$(var.myProject.TargetFileName)" /privileges=user' Impersonate="yes" /&gt;
  </code></pre>
  
  <p>However, if I re-run my installer and select 'Remove', it uninstalls fine. Also, If I run the uninstall from a command line (using the msiexec command found in the registry entry for this product), it also uninstalls fine.</p>
  
  <p><strong>Also:</strong></p>
  
  <ul>
  <li>This only happens in Windows 10. Older versions of Windows are fine.</li>
  <li>I have replicated on several machines, including a fresh install.</li>
  <li>I have an older installer (a VS2010 Setup Project), the problem happens with that installer as well.</li>
  <li>I have tried with UAC at different elevations, no difference.</li>
  <li>I have seen other posts here about changing the <strong>Impersonate</strong> setting to "no", no difference.</li>
  </ul>
  
  <p>It seems to me that there is a problem with the new <strong>Windows Apps &amp; Features</strong> app, but I have yet to find anything on the Microsoft forums.</p>
  
  <p><strong>Update:</strong></p>
  
  <p>A Wix user posted this: <a href="http://blog.iswix.com/2015/08/dtf-bug-with-new-windows-10-apps-and.html" rel="nofollow">DTF Bug with new Windows 10 Apps and Features</a>. Also, we have tried a variety of commands (thinking it was a UAC issue), none of them work, even 'built-in' Windows commands fail.</p>