There is already an open DataReader associated with this Command which must be closed first.

Details
Written by: Stanko Milosev
Category: MVC 3
Hits: 4402
If you are receiving error message as in title, then in connection string add:

multipleactiveresultsets=True

Something like: 

<add name="MyDbContext" 
connectionString="
  Data Source=myServer;Initial Catalog=MyDb;
  Persist Security Info=True;
  Integrated Security=True;
  multipleactiveresultsets=True
" />