Error while executing db.Database.Migrate(): Incorrect syntax near the keyword 'NOT'

Here's my Dataseeder class:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using StackStore.Data;
using System.Collections.Generic;
using System.Linq;

namespace StackStore.Models
{
    // http://stackoverflow.25lm.com/questions/34536021/seed-initial-data-in-entity-framework-7-rc-1-and-asp-net-mvc-6
    public static class DataSeeder // EntityFramework 7.0 DataSeeder
    {
        // TODO: Move this code when seed data is implemented in EF 7

        /// <summary>
        /// This is a workaround for missing seed data functionality in EF 7.0-rc1
        /// More info: https://github.com/aspnet/EntityFramework/issues/629
        /// </summary>
        /// <param name="app">
        /// An instance that provides the mechanisms to get instance of the database context.
        /// </param>
        public static async void SeedData(this IApplicationBuilder app)
        {
            var db = app.ApplicationServices.GetService<ApplicationDbContext>();

            //Caution: Clear all the tables in the database first.
            db.Database.Migrate();


            db.SaveChanges();
        }
    }
}

Basically, the error hits at db.Database.Migrate() and it throws me this chunk which I have completely no idea about. I've been trying my best to look for the source of the error but to no avail. Even attempting to check the definitions of the migrate method.

Here's the error:

System.Data.SqlClient.SqlException was unhandled by user code
  Class=15
  HResult=-2146232060
  LineNumber=7
  Message=Incorrect syntax near the keyword 'NOT'.
  Number=156
  Procedure=""
  Server=NIXHOLAS\SQLEXPRESS
  Source=Core .Net SqlClient Data Provider
  State=1
  StackTrace:
       at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
       at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
       at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
       at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
       at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite, String methodName)
       at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
       at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.Execute(IRelationalConnection connection, String executeMethod, IReadOnlyDictionary`2 parameterValues, Boolean openConnection, Boolean closeConnection)
       at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues, Boolean manageConnection)
       at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1 migrationCommands, IRelationalConnection connection)
       at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration)
       at StackStore.Models.DataSeeder.<SeedData>d__0.MoveNext() in C:\Users\nixho\StackStore\src\StackStore\Models\DataSeeder.cs:line 36
  InnerException: 


  Microsoft.EntityFrameworkCore.DbUpdateException was unhandled by user code
  HResult=-2146233088
  Message=An error occurred while updating the entries. See the inner exception for details.
  Source=Microsoft.EntityFrameworkCore.Relational
  StackTrace:
       at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.<ExecuteAsync>d__32.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.Update.Internal.BatchExecutor.<ExecuteAsync>d__1.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.<SaveChangesAsync>d__47.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.ChangeTracking.Internal.StateManager.<SaveChangesAsync>d__45.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.EntityFrameworkCore.DbContext.<SaveChangesAsync>d__30.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.AspNetCore.Identity.EntityFrameworkCore.RoleStore`5.<SaveChanges>d__14.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.AspNetCore.Identity.EntityFrameworkCore.RoleStore`5.<CreateAsync>d__15.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at Microsoft.AspNetCore.Identity.RoleManager`1.<CreateAsync>d__30.MoveNext()
    --- End of stack trace from previous location where exception was thrown ---
       at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
       at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
       at StackStore.Models.DataSeeder.<SeedData>d__0.MoveNext() in C:\Users\nixho\StackStore\src\StackStore\Models\DataSeeder.cs:line 44
  InnerException: 
       Class=16
       HResult=-2146232060
       LineNumber=2
       Message=Invalid object name 'AspNetRoles'.
       Number=208
       Procedure=""
       Server=NIXHOLAS\SQLEXPRESS
       Source=Core .Net SqlClient Data Provider
       State=1
       StackTrace:
            at System.Data.SqlClient.SqlCommand.<>c.<ExecuteDbDataReaderAsync>b__107_0(Task`1 result)
            at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
            at System.Threading.Tasks.Task.Execute()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
            at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.<ExecuteAsync>d__20.MoveNext()
         --- End of stack trace from previous location where exception was thrown ---
            at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
            at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
            at Microsoft.EntityFrameworkCore.Update.ReaderModificationCommandBatch.<ExecuteAsync>d__32.MoveNext()
       InnerException: