Adding a case when the class name for entity used in entity framework is same as class name for a web form code-behind file.

Suppose you have a web form Contact.aspx whose codebehind class is Contact and you have an entity name Contact.

Then following code will throw a NullReferenceException when you call context.SaveChanges()

Contact contact = new Contact { Name = "Abhinav"};
var context = new DataContext();
context.Contacts.Add(contact);
context.SaveChanges(); // NullReferenceException at this line

For the sake of completeness DataContext class

public class DataContext : DbContext 
{
    public DbSet<Contact> Contacts {get; set;}
}

and Contact entity class. Sometimes entity classes are partial classes so that you can extend them in other files too.

public partial class Contact 
{
    public string Name {get; set;}
}

The error occurs when both the entity and codebehind class are in same namespace. To fix this, rename the entity class or the codebehind class for Contact.aspx.

Reason I am still not sure about the reason. But whenever any of the entity class will extend System.Web.UI.Page this error occurs.

For discussion have a look at NullReferenceException in DbContext.saveChanges()

Adding a case when the class name for entity used in entity framework is same as class name for a web form code-behind file.

Suppose you have a web form Contact.aspx whose codebehind class is Contact and you have an entity name Contact.

Then following code will throw a NullReferenceException when you call context.SaveChanges()

Contact contact = new Contact { Name = "Abhinav"};
var context = new DataContext();
context.Contacts.Add(contact);
context.SaveChanges(); // NullReferenceException at this line

For the sake of completeness DataContext class

public class DataContext : DbContext 
{
    public DbSet<Contact> Contacts {get; set;}
}

and Contact entity class. Sometimes entity classes are partial classes so that you can extend them in other files too.

public partial class Contact 
{
    public string Name {get; set;}
}

The error occurs when both the entity and codebehind class are in same namespace. To fix this, rename the entity class or the codebehind class for Contact.aspx.

Reason I am still not sure about the reason. But whenever any of the entity class will extend System.Web.UI.Page this error occurs.

For discussion have a look at NullReferenceException in DbContext.saveChanges()

Adding a case when the class name for entity used in entity framework is same as class name for a web form code-behind file.

Suppose you have a web form Contact.aspx whose codebehind class is Contact and you have an entity name Contact.

Then following code will throw a NullReferenceException when you call context.SaveChanges()

Contact contact = new Contact { Name = "Abhinav"};
var context = new DataContext();
context.Contacts.Add(contact);
context.SaveChanges(); // NullReferenceException at this line

For the sake of completeness DataContext class

public class DataContext : DbContext 
{
    public DbSet<Contact> Contacts {get; set;}
}

and Contact entity class

public class Contact 
{
    public string Name {get; set;}
}

To fix this, rename the entity class or the codebehind class for Contact.aspx.

For discussion have a look at NullReferenceException in DbContext.saveChanges()

Adding a case when the class name for entity used in entity framework is same as class name for a web form code-behind file.

Suppose you have a web form Contact.aspx whose codebehind class is Contact and you have an entity name Contact.

Then following code will throw a NullReferenceException when you call context.SaveChanges()

Contact contact = new Contact { Name = "Abhinav"};
var context = new DataContext();
context.Contacts.Add(contact);
context.SaveChanges(); // NullReferenceException at this line

For the sake of completeness DataContext class

public class DataContext : DbContext 
{
    public DbSet<Contact> Contacts {get; set;}
}

and Contact entity class. Sometimes entity classes are partial classes so that you can extend them in other files too.

public partial class Contact 
{
    public string Name {get; set;}
}

The error occurs when both the entity and codebehind class are in same namespace. To fix this, rename the entity class or the codebehind class for Contact.aspx.

Reason I am still not sure about the reason. But whenever any of the entity class will extend System.Web.UI.Page this error occurs.

For discussion have a look at NullReferenceException in DbContext.saveChanges()