How to fix MERGE statement conflicted with the FOREIGN KEY constraint - sql-server

Question

I'm trying to get some tables:
The migration was:
migrationBuilder.CreateTable(
name: "Products",
columns: table => new
{
Id = table.Column<int>(type: "int", nullable: false)
.Annotation("SqlServer:Identity", "1, 1"),
Name = table.Column<string>(type: "nvarchar(max)", nullable: true),
Description = table.Column<string>(type: "nvarchar(max)", nullable: true),
Version = table.Column<string>(type: "nvarchar(max)", nullable: true),
ReleaseDate = table.Column<DateTime>(type: "datetime2", nullable: false),
IsReleased = table.Column<bool>(type: "bit", nullable: false),
IsActive = table.Column<bool>(type: "bit", nullable: false),
IsDeleted = table.Column<bool>(type: "bit", nullable: false),
Created = table.Column<DateTime>(type: "datetime2", nullable: false),
Modified = table.Column<DateTime>(type: "datetime2", nullable: false),
RowVersion = table.Column<byte[]>(type: "rowversion", rowVersion: true, nullable: true),
TestText = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true)
},
constraints: table =>
{
table.PrimaryKey("PK_Products", x => x.Id);
});
migrationBuilder.CreateTable(
name: "Licenses",
columns: table => new
{
Id = table.Column<int>(type: "int", nullable: false)
.Annotation("SqlServer:Identity", "1, 1"),
Licensenumber = table.Column<string>(type: "varchar(50)", maxLength: 50, nullable: false),
ProductId = table.Column<int>(type: "int", nullable: false),
UserId = table.Column<int>(type: "int", nullable: false),
Created = table.Column<DateTime>(type: "datetime2", nullable: false),
Modified = table.Column<DateTime>(type: "datetime2", nullable: false),
RowVersion = table.Column<byte[]>(type: "rowversion", rowVersion: true, nullable: true),
TestText = table.Column<string>(type: "nvarchar(50)", maxLength: 50, nullable: true)
},
constraints: table =>
{
table.PrimaryKey("PK_Licenses", x => x.Id);
table.ForeignKey(
name: "FK_Licenses_Products_ProductId",
column: x => x.ProductId,
principalTable: "Products",
principalColumn: "Id",
onDelete: ReferentialAction.Cascade);
table.ForeignKey(
name: "FK_Licenses_Users_UserId",
column: x => x.UserId,
principalTable: "Users",
principalColumn: "Id",
onDelete: ReferentialAction.Cascade);
});
Now i'm getting while database creation: MERGE statement conflicted with the FOREIGN KEY constraint "FK_Licenses_Products_ProductId". The conflict occurred in database "app-licenseserver", table "dbo.Products", column 'Id'.
But what happend? Can i fix it?

Answer 1

It means there is no row in the Products table that matches the Id of the row of the entry you're trying to insert (merge).
Through your comments, it looks like you discovered a problem that left your products table empty but I wanted to add this:
Note: in your model the ProductId foreign key is not nullable, therefore if you don't set it, it will default to 0 and if that Id does not exist, you will also get this error.
This particular issue is what brought me to your question.