Entity Framework error: Cannot insert explicit value for identity column in table
I have run into this before. This error means you are trying to assign a value explicitly to a column where the database automatically assigns it.
Suggestion: Update your edmx file to reflect any changes you may have made in the database. If the database automatically assigns the value, you should see the "IsDbGenerated=true" attribute in your designer file under that property. If it's not there, you can add it manually.
Try this:
using System.ComponentModel.DataAnnotations.Schema;
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public decimal Identity_Col { get; set; }
The Entity Framework class file adds these lines of code to the Identity column.
Put these attribs on top of the property which is identity:
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int ID { get; set; }