i tried to update my migration but then an error occurred

The ALTER TABLE statement conflicted with the FOREIGN KEY constraint “FK_ClassSessionsDetails_PeopleTypes_PeopleTypeId”. The conflict occurred in database “cap_web”, table “dbo.PeopleTypes”, column ‘Id’.

There seems to be no existing foreign key between ClassSessionsDetails and PeopleTypes, but I’m still getting this conflict error.

this is my migration code looks like:

using Microsoft.EntityFrameworkCore.Migrations;

#nullable disable

namespace BlazorApp1.Migrations
{
    /// <inheritdoc />
    public partial class peopletypetocsd : Migration
    {
        /// <inheritdoc />
        protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.AddColumn<int>(
                name: "PeopleTypeId",
                table: "ClassSessionsDetails",
                type: "int",
                nullable: false,
                defaultValue: 0);

            migrationBuilder.CreateIndex(
                name: "IX_ClassSessionsDetails_PeopleTypeId",
                table: "ClassSessionsDetails",
                column: "PeopleTypeId");

            migrationBuilder.AddForeignKey(
                name: "FK_ClassSessionsDetails_PeopleTypes_PeopleTypeId",
                table: "ClassSessionsDetails",
                column: "PeopleTypeId",
                principalTable: "PeopleTypes",
                principalColumn: "Id");
        }

        /// <inheritdoc />
        protected override void Down(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropForeignKey(
                name: "FK_ClassSessionsDetails_PeopleTypes_PeopleTypeId",
                table: "ClassSessionsDetails");

            migrationBuilder.DropIndex(
                name: "IX_ClassSessionsDetails_PeopleTypeId",
                table: "ClassSessionsDetails");

            migrationBuilder.DropColumn(
                name: "PeopleTypeId",
                table: "ClassSessionsDetails");
        }
    }
}

does anyone know what might be missing here?