title: Unable to install exenstions and updates for Visual Studio 2017 RC (15.0.26014.0)
body: <p>I recently installed  Visual Studio 2017 RC (15.0.26014.0) and was trying to install extensions. However while installing any extension using Tools->Extensions and Updates menu fails. Following is installation log. </p>
  
  <pre><code>27-Dec-16 10:35:19 AM - Beginning to install extension to Microsoft Visual  Studio Enterprise 2017 RC...
  27-Dec-16 10:35:19 AM - Install Error : System.IO.FileNotFoundException: Unable to find the specified file.
  at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.GetCurrentSetupInstance()
  at  Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.PerformSetupEngineInstall(InstallableExtensionImpl extension, Boolean installPerMachine, Boolean isPackComponent, IDictionary`2 extensionsInstalledSoFar, List`1 extensionsUninstalledSoFar, IInstalledExtensionList modifiedInstalledExtensionsList, IProgress`1 progress, InstallFlags installFlags, AsyncOperation asyncOp, IInstalledExtension&amp; newExtension)
  Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.InstallInternal    (InstallableExtensionImpl extension, InstallFlags installFlags, IDictionary`2 extensionsInstalledSoFar, List`1 extensionsUninstalledSoFar,
  IInstalledExtensionList modifiedInstalledExtensionsList, AsyncOperation asyncOp, IProgress`1 progress)
  at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.BeginInstall(IInstallableExtension installableExtension, InstallFlags installFlags, AsyncOperation asyncOp)
  at Microsoft.VisualStudio.ExtensionManager.ExtensionEngineImpl.InstallWorker(IInstallableExtension extension, InstallFlags installFlags, AsyncOperation asyncOp)
  </code></pre>
  
  <p>I checked and found corresponding VSIX file is present in temp folder (C:\Users\xxxxx\AppData\Local\Temp)</p>