title: wix 3.x - Failed to load xml file
body: <p>I have a WIX package - created using Wix Toolset 3.7, which is strangely failing on a specific environment with the following message,</p>
  
  <blockquote>
    <p>ExecXmlFile:  Error 0x80070005: failed to load XML file:
    \sharep001\share\IIS\pre\EAT\Website\CalculationService\Web.config</p>
    
    <p>MSI (s) (70!FC) [11:15:37:491]: Product: EAT 1.0.0.0 -- Error 25531.
    Failed to open XML file
    \sharep001\share\IIS\pre\EAT\Website\CalculationService\Web.config,
    system error: -2147024891</p>
    
    <p>Error 25531. Failed to open XML file
    \sharep001\share\IIS\pre\EAT\Website\CalculationService\Web.config,
    system error: -2147024891</p>
    
    <p>CustomAction ExecXmlFile returned actual error code 1603 (note this
    may not be 100% accurate if translation happened inside sandbox)</p>
  </blockquote>
  
  <p>Why I say the behavior is strange is because,</p>
  
  <ol>
  <li>The same package I can install on the local directory on the webserver, no errors reported.</li>
  <li>The same package I can install on another UNC directory, no errors reported.</li>
  </ol>
  
  <p>Why is it failing?
  - The XML transform step only gets called after the directory is created, files are dropped, iis website is created, etc. So, hard to explain why, does not seem like a permission issue. </p>
  
  <p>Any idea how I can debug this? </p>