ASP.NET Core project with EF Core and database context. Entity classes defining database tables. Database provider configuration in Startup.cs or appsettings.json
Error occurs when LINQ query uses null IEnumerable parameter. Incorrect connection string configuration can trigger the error. Missing set; in DbContext causes the issue. Using Count() without checking for null causes the error
Error occurs when attempting to insert values into identity columns. Error message states "Cannot insert explicit value for identity column"
Entity Framework is Microsoft's open-source ORM framework written in C#. First released on August 11, 2008. Handles database connection and object-relational mapping
Entity Framework tracks entities in five states: Added, Unchanged, Modified, Deleted, Detached. Unchanged entities are not touched by SaveChanges. Added entities are inserted into database and become Unchanged. Modified entities are updated in database and become Unchanged. Deleted entities are deleted from database and detached from context
Error occurs when assigning value to nullable property without value. Can happen when property isn't initialized or has default value. Error appears when property is explicitly set to null