Solution for “SharePoint Designer cannot display the item” error to edit workflow

If you are unable to edit workflows in SharePoint 2013 after upgrading from 2010 and getting following error then perform  the steps mentioned below to resolve this issue.

1. Make sure you have uninstalled SharePoint Designer 2010
2. Close SharePoint Designer 2013
3. On the local computer, browse to the following folder:
   • C:\Users\<Replace Your User Name>\AppData\Local\Microsoft\WebsiteCache
   • Example: C:\Users\mark.lee.contoso\AppData\Local\Microsoft\WebsiteCache
4. Delete everything in WebsiteCache folder.
5. On the local computer, browse to the following folder:
   • C:\Users\<Replace Your User Name>\AppData\Roaming\Microsoft\SharePoint Designer\ProxyAssemblyCache
   • Example: C:\Users\mark.lee.contoso\AppData\Roaming\Microsoft\SharePoint Designer\ProxyAssemblyCache
6. Delete everything in ProxyAssemblyCache folder.
7. Done.
8. Open SharePoint Designer 2013 and make the changes to your site as needed.

This happens due to cached .NET assemblies in above mentioned folders. These cached files confuses  SPD2013 to use older .NET code which is not compatible with SP2013.