.net Core 3.1 Identity: SqlException: Invalid column name 'Discriminator'. Invalid column name 'Discriminator'

This is occurring directly after login. I've done some reading (61790251 29778041 20008827), but do not know where to apply [NotMapped], or if I should. I had been modifying ApplicationUserRole and IdentityContext but reverted or commented those changes.

Exception

I don't understand how to work out the problem from the Exception.

Microsoft.Data.SqlClient.SqlException (0x80131904): Invalid column name 'Discriminator'.
Invalid column name 'Discriminator'.
   at Microsoft.Data.SqlClient.SqlCommand.<>c.<ExecuteDbDataReaderAsync>b__164_0(Task`1 result)
   at System.Threading.Tasks.ContinuationResultTaskFromResultTask`2.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Storage.RelationalCommand.ExecuteReaderAsync(RelationalCommandParameterObject parameterObject, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.InitializeReaderAsync(DbContext _, Boolean result, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.SqlServer.Storage.Internal.SqlServerExecutionStrategy.ExecuteAsync[TState,TResult](TState state, Func`4 operation, Func`4 verifySucceeded, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryingEnumerable`1.AsyncEnumerator.MoveNextAsync()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.ToListAsync[TSource](IQueryable`1 source, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Identity.EntityFrameworkCore.UserStore`9.GetRolesAsync(TUser user, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Identity.UserManager`1.GetRolesAsync(TUser user)
   at Microsoft.AspNetCore.Identity.UserClaimsPrincipalFactory`2.GenerateClaimsAsync(TUser user)
   at Microsoft.AspNetCore.Identity.UserClaimsPrincipalFactory`1.CreateAsync(TUser user)
   at FleetLogix.Intranet.Identity.CustomClaimsPrincipalFactory.CreateAsync(ApplicationUser user) in C:\Users\lukem\source\FleetLogix.Intranet\FleetLogix.Intranet\Identity\CustomClaimsPrincipalFactory.cs:line 32
   at Microsoft.AspNetCore.Identity.SignInManager`1.CreateUserPrincipalAsync(TUser user)
   at Microsoft.AspNetCore.Identity.SignInManager`1.SignInWithClaimsAsync(TUser user, AuthenticationProperties authenticationProperties, IEnumerable`1 additionalClaims)
   at Microsoft.AspNetCore.Identity.SignInManager`1.SignInOrTwoFactorAsync(TUser user, Boolean isPersistent, String loginProvider, Boolean bypassTwoFactor)
   at Microsoft.AspNetCore.Identity.SignInManager`1.PasswordSignInAsync(TUser user, String password, Boolean isPersistent, Boolean lockoutOnFailure)
   at Microsoft.AspNetCore.Identity.SignInManager`1.PasswordSignInAsync(String userName, String password, Boolean isPersistent, Boolean lockoutOnFailure)
   at FleetLogix.Intranet.Areas.Identity.Pages.Account.LoginModel.OnPostAsync(String returnUrl) in C:\Users\lukem\source\FleetLogix.Intranet\FleetLogix.Intranet\Areas\Identity\Pages\Account\Login.cshtml.cs:line 83
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.ExecutorFactory.GenericTaskHandlerMethod.Convert[T](Object taskAsObject)
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.ExecutorFactory.GenericTaskHandlerMethod.Execute(Object receiver, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.InvokeHandlerMethodAsync()
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.InvokeNextPageFilterAsync()
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.Rethrow(PageHandlerExecutedContext context)
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.RazorPages.Infrastructure.PageActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeNextResourceFilter>g__Awaited|24_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Rethrow(ResourceExecutedContextSealed context)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeFilterPipelineAsync>g__Awaited|19_0(ResourceInvoker invoker, Task lastTask, State next, Scope scope, Object state, Boolean isCompleted)
   at Microsoft.AspNetCore.Mvc.Infrastructure.ResourceInvoker.<InvokeAsync>g__Awaited|17_0(ResourceInvoker invoker, Task task, IDisposable scope)
   at Microsoft.AspNetCore.Routing.EndpointMiddleware.<Invoke>g__AwaitRequestTask|6_0(Endpoint endpoint, Task requestTask, ILogger logger)
   at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)
ClientConnectionId:08790246-e0a5-404b-b00f-a6e711f2097d
Error Number:207,State:1,Class:16

LogError

This pointed me at the UserRoles

Microsoft.EntityFrameworkCore.Database.Command: Error: Failed executing DbCommand (10ms) [Parameters=[@__userId_0='?' (DbType = Int32)], CommandType='Text', CommandTimeout='30']
SELECT [a0].[Name]
FROM [AspNetUserRoles] AS [a]
INNER JOIN [AspNetRoles] AS [a0] ON [a].[RoleId] = [a0].[Id]
WHERE [a].[Discriminator] IN (N'IdentityUserRole<int>', N'ApplicationUserRole') AND ([a].[UserId] = @__userId_0)

ApplicationUserRole

I had planned to add a Date property to make tracking when a role had been added. Commented it out.

public class ApplicationUserRole : IdentityUserRole<int>
{

    public ApplicationUserRole() : base()
    { }

    public ApplicationUserRole(int roleId, int userId) : base()
    {
        base.UserId = userId;
        base.RoleId = roleId;
    }

    //[DisplayName("Last Modified")]
    //[DataType(DataType.DateTime)]
    //[DisplayFormat(ApplyFormatInEditMode = true, DataFormatString = "{0:yyyy-MM-dd hh:mm:ss}")]
    //public DateTime LastModified { get; set; }

    [ForeignKey("UserId")]
    public virtual ApplicationUser User { get; set; }

    [ForeignKey("RoleId")]
    public virtual ApplicationRole Role { get; set; }
}

IdentityContext

Had a section in the builder for the UserRole stuff. Commented out.

public class IdentityContext : IdentityDbContext<ApplicationUser, ApplicationRole, int>
{
    private readonly IConfiguration _config;

    public IdentityContext(IConfiguration config, DbContextOptions<IdentityContext> options)
        : base(options)
    {
        _config = config ?? throw new System.ArgumentNullException(nameof(config));
    }

    public DbSet<ApplicationUser> ApplicationUsers { get; set; }

    public DbSet<ApplicationRole> ApplicationRoles { get; set; }

    //public DbSet<ApplicationUserRole> ApplicationUserRoles { get; set; }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        if (builder == null)
        {
            throw new ArgumentNullException(nameof(builder));
        }
        base.OnModelCreating(builder);

        // Add your customizations after calling base.OnModelCreating(builder);

        /*
        builder.Entity<ApplicationUserRole>(userRole =>
        {
            userRole.HasKey(ur => new { ur.UserId, ur.RoleId });

            userRole.HasOne(ur => ur.Role)
                .WithMany(r => r.UserRoles)
                .HasForeignKey(ur => ur.RoleId)
                .IsRequired();

            userRole.HasOne(ur => ur.User)
                .WithMany(r => r.UserRoles)
                .HasForeignKey(ur => ur.UserId)
                .IsRequired();
        });
        */
    }
}

What do I need to do to fix this?