title: ASP.Net cannot create/shadow copy in PRODUCTION
body: <p>We've recently updated a fairly large ASP.NET website (~1500th alexa traffic ranking) to use VS2010 and .NET 4.0 running on Windows Server 2008 R2</p>
  
  <p>Since then, when we deploy new versions of the site we occasionally noticed the same error in this post:
  <a href="https://stackoverflow.com/questions/1007200/asp-net-cannot-create-shadow-copy">ASP.Net cannot create/shadow copy</a>
  The error message is:
  Cannot create/shadow copy 'xxxx, Version=4.0.4301.26898, Culture=neutral, PublicKeyToken=null' when that file already exists</p>
  
  <p>However, unlike in that post, the error is occurring only in our production environments &amp; only on some servers.</p>
  
  <p>After we ship a new version of the code, we recycle all AppPools and the error starts occuring.</p>
  
  <p>A further AppPool recycle seems to fix the issue, however I really want to know how we can avoid this problem in the first place?</p>