Our Application is an MVC Application. We are using Entity Framework. When I am updating the model to add a table from the database. I am recieving an exception and it says
"An exception of type 'System.ArgumentException' occured while attempting to update from the database. The exception message is: 'An entry with the same key already exists'."
I am not able to figure out what is the problem. Can I have a solution to get over the problem.
This is a more detailed answer based on Tazos333's answer.
Finding the actual duplicate is the hardest part. Using Powershell it can be done by:
Get-Content .\models.edmx | Group-Object | Where-Object { $_.Count -gt 1 } | Select -ExpandProperty Name
In order to get as few false positive results as possible, run this only for the <!-- C-S mapping content --> section (copy-pasted in other text file).
Besides scalar properties duplicates (quite normal, since tables might contain the same column names), the duplicate <EntitySetMapping Name="..."> will be very obvious.