title: FileNotFoundException when transforming T4 Template
body: <p>I am using an existing T4 Template that I last used about 6 months ago and I'm not aware of anything having changed. However I am not getting the following exception, when I save the template file:</p>
  
  <blockquote>
    <p>Errors were generated when initializing the transformation object. The
    transformation will not be run.  The following Exception was thrown:
    System.IO.FileNotFoundException: Could not load file or assembly
    'T4Toolbox, Version=11.0.0.0, Culture=neutral,
    PublicKeyToken=dc4a538672a7b38f' or one of its dependencies. The
    system cannot find the file specified. File name: '<strong>T4Toolbox,
    Version=11.0.0.0</strong>, Culture=neutral, PublicKeyToken=dc4a538672a7b38f'</p>
    
    <p>Server stack trace:     at
    System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String
    codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint,
    StackCrawlMark&amp; stackMark, IntPtr pPrivHostBinder, Boolean
    throwOnFileNotFound, Boolean forIntrospection, Boolean
    suppressSecurityChecks) ...</p>
  </blockquote>
  
  <p>The header for my tt file is:</p>
  
  <pre><code>&lt;#@ template language="C#" debug="True" #&gt;
  &lt;#@ output extension="cs" #&gt;
  &lt;#@ include file="T4Toolbox.tt" #&gt;
  &lt;#@ assembly name="System.Core" #&gt;
  &lt;#@ import namespace="System.IO" #&gt;
  &lt;#@ assembly name="System.Xml"#&gt;
  &lt;#@ assembly name="System.Linq"#&gt;
  &lt;#@ assembly name="$(TargetPath)" #&gt;
  &lt;#@ import namespace="System.Xml" #&gt;
  &lt;#@ import namespace="System.Diagnostics" #&gt;
  &lt;#@ import namespace="System.Linq" #&gt;
  &lt;#@ import namespace="System.Collections.ObjectModel" #&gt;
  &lt;#@ import namespace="MyNamespace" #&gt;
  &lt;#@ parameter name="className" type="System.String" #&gt;
  </code></pre>
  
  <p>I have checked Tools > Extension and Updates and I have Version 11.8.0.0 installed.</p>
  
  <p>Is there anything else I can check?</p>