Asp.net core 2.1 crashing due to model InverseProperty

Question

My site is crashing on load with an extremely long unhandled exception in System.Reflection on the first call to the DbContext.

Using ef-core 2.1 rc1

System.ArgumentNullException: Value cannot be null.
Parameter name: type
   at System.Reflection.IntrospectionExtensions.GetTypeInfo(Type type)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.InversePropertyAttributeConvention.ConfigureInverseNavigation(InternalEntityTypeBuilder entityTypeBuilder, MemberInfo navigationMemberInfo, InternalEntityTypeBuilder targetEntityTypeBuilder, InversePropertyAttribute attribute)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.InversePropertyAttributeConvention.Apply(InternalEntityTypeBuilder entityTypeBuilder, PropertyInfo navigationPropertyInfo, Type targetClrType, InversePropertyAttribute attribute)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.NavigationAttributeEntityTypeConvention`1.Apply(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ImmediateConventionScope.OnEntityTypeAdded(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.RunVisitor.VisitOnEntityTypeAdded(OnEntityTypeAddedNode node)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnEntityTypeAddedNode.Accept(ConventionVisitor visitor)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionVisitor.Visit(ConventionNode node)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionVisitor.VisitConventionScope(ConventionScope node)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionBatch.Run()
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ConventionBatch.Dispose()
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.RelationshipDiscoveryConvention.DiscoverRelationships(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.RelationshipDiscoveryConvention.Apply(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ImmediateConventionScope.OnEntityTypeAdded(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnEntityTypeAdded(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(EntityType entityType)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(Type type, ConfigurationSource configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(TypeIdentity& type, ConfigurationSource configurationSource, Boolean throwOnQuery)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(Type type, ConfigurationSource configurationSource, Boolean throwOnQuery)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.InversePropertyAttributeConvention.Apply(InternalEntityTypeBuilder entityTypeBuilder, PropertyInfo navigationPropertyInfo, Type targetClrType, InversePropertyAttribute attribute)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.NavigationAttributeEntityTypeConvention`1.Apply(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.ImmediateConventionScope.OnEntityTypeAdded(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Conventions.Internal.ConventionDispatcher.OnEntityTypeAdded(InternalEntityTypeBuilder entityTypeBuilder)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(EntityType entityType)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.Model.AddEntityType(Type type, ConfigurationSource configurationSource)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(TypeIdentity& type, ConfigurationSource configurationSource, Boolean throwOnQuery)
   at Microsoft.EntityFrameworkCore.Metadata.Internal.InternalModelBuilder.Entity(Type type, ConfigurationSource configurationSource, Boolean throwOnQuery)
   at Microsoft.EntityFrameworkCore.ModelBuilder.Entity(Type type)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelCustomizer.FindSets(ModelBuilder modelBuilder, DbContext context)
   at Microsoft.EntityFrameworkCore.Infrastructure.RelationalModelCustomizer.FindSets(ModelBuilder modelBuilder, DbContext context)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelCustomizer.Customize(ModelBuilder modelBuilder, DbContext context)
   at Microsoft.EntityFrameworkCore.Infrastructure.RelationalModelCustomizer.Customize(ModelBuilder modelBuilder, DbContext context)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.CreateModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.<>c__DisplayClass5_0.<GetModel>b__1()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
   at System.Lazy`1.ExecutionAndPublication(LazyHelper executionAndPublication, Boolean useDefaultConstructor)
   at System.Lazy`1.CreateValue()
   at Microsoft.EntityFrameworkCore.Infrastructure.ModelSource.GetModel(DbContext context, IConventionSetBuilder conventionSetBuilder, IModelValidator validator)
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.CreateModel()
   at Microsoft.EntityFrameworkCore.Internal.DbContextServices.get_Model()
   at Microsoft.EntityFrameworkCore.Infrastructure.EntityFrameworkServicesBuilder.<>c.<TryAddCoreServices>b__7_1(IServiceProvider p)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitFactory(FactoryCallSite factoryCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitConstructor(ConstructorCallSite constructorCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteRuntimeResolver.VisitScoped(ScopedCallSite scopedCallSite, ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.CallSiteVisitor`2.VisitCallSite(IServiceCallSite callSite, TArgument argument)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.DynamicServiceProviderEngine.<>c__DisplayClass1_0.<RealizeService>b__0(ServiceProviderEngineScope scope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngine.GetService(Type serviceType, ServiceProviderEngineScope serviceProviderEngineScope)
   at Microsoft.Extensions.DependencyInjection.ServiceLookup.ServiceProviderEngineScope.GetService(Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService(IServiceProvider provider, Type serviceType)
   at Microsoft.Extensions.DependencyInjection.ServiceProviderServiceExtensions.GetRequiredService[T](IServiceProvider provider)
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.get_Model()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityType()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityQueryable()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Linq.IQueryable.get_Provider()
   at Microsoft.EntityFrameworkCore.EntityFrameworkQueryableExtensions.AsNoTracking[TEntity](IQueryable`1 source)
   at Ctrack.ReportGroups.Pages.IndexModel.OnGetAsync() in C:\Users\lukem\Documents\Visual Studio 2017\Projects\Ctrack.ReportGroups\Ctrack.ReportGroups\Pages\Index.cshtml.cs:line 34
   at Microsoft.AspNetCore.Mvc.RazorPages.Internal.ExecutorFactory.NonGenericTaskHandlerMethod.Execute(Object receiver, Object[] arguments)
   at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeHandlerMethodAsync()
   at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeNextPageFilterAsync()
   at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.Rethrow(PageHandlerExecutedContext context)
   at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.RazorPages.Internal.PageActionInvoker.InvokeInnerFilterAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeNextResourceFilter()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Rethrow(ResourceExecutedContext context)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.Next(State& next, Scope& scope, Object& state, Boolean& isCompleted)
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeFilterPipelineAsync()
   at Microsoft.AspNetCore.Mvc.Internal.ResourceInvoker.InvokeAsync()
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Session.SessionMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Authentication.AuthenticationMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.MigrationsEndPointMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

The issue may be related to the configuration of Inverse Properties (based on the 2nd at statement)

Group

Last 2 fields are inverse

[Table("Report_Group")]
public class Group
{
    [Key, Required, Column("GroupId")]
    public int Id { get; set; }

    [Required, MaxLength(5)]
    public string OrgCode  { get; set; }

    [Required, MaxLength(100)]
    public string Name { get; set; }

    public int TierId { get; set; }

    public int? ParentGroupId { get; set; }

    public int? CostCenter { get; set; }

    [Required]
    public int ExcludeFromAlertStats { get; set; }

    [Required]
    public int GroupTypeId { get; set; }

    [ForeignKey("ParentGroupId")]
    public virtual Group Parent { get; set; }

    [ForeignKey("OrgCode")]
    public virtual Organisation Organisation { get; set; }

    [ForeignKey("TierId")]
    public virtual Tier Tier { get; set; }

    [ForeignKey("GroupTypeId")]
    public virtual GroupType GroupType { get; set; }

    [InverseProperty("GroupId")]
    public virtual IList<GroupToUnitLink> UnitLinks { get; set; }

    [InverseProperty("GroupId")]
    public virtual IList<GroupToContactLink> ContactLinks { get; set; }
}

GroupToContactLink

Many to Many link table. No InverseProperty's. Included for reference

[Table("Report_Link_Group_to_Contact")]
public class GroupToContactLink
{
    public GroupToContactLink()
    {
    }

    public GroupToContactLink(int contactId, int groupId, int linkTypeId)
    {
        this.ContactId = contactId;
        this.GroupId = groupId;
        this.LinkTypeId = linkTypeId;
    }

    [Required]
    public int ContactId { get; set; }

    [Required]
    public int GroupId { get; set; }

    [Required]
    public int LinkTypeId { get; set; }

    [ForeignKey("ContactId")]
    public virtual Contact Contact { get; set; }

    [ForeignKey("GroupId")]
    public virtual Group Group { get; set; }

    [ForeignKey("LinkTypeId")]
    public virtual ContactLinkType LinkType { get; set; }

}

GroupToUnitLink

Many to Many link table. No InverseProperty's. Included for reference

[Table("Report_Link_Group_to_Unit")]
public class GroupToUnitLink
{
    [Required]
    public int NodeId { get; set; }

    [Required]
    public int GroupId { get; set; }

    public GroupToUnitLink()
    { }

    public GroupToUnitLink(int nodeId, int groupId)
    {
        this.NodeId = nodeId;
        this.GroupId = groupId;
    }

    [ForeignKey("NodeId")]
    public virtual Unit Unit { get; set; }

    [ForeignKey("GroupId")]
    public virtual Group Group { get; set; }

}

Contact

Also has an InverseProperty

[Table("Report_Contact")]
public class Contact
{
    [Key, Column("ContactId")]
    public int Id { get; set; }

    [Required, StringLength(5)]
    public string OrgCode { get; set; }

    [Required, StringLength(100)]
    public string Name { get; set; }

    [StringLength(12)]
    public string Phone { get; set; }

    [StringLength(255), EmailAddress]
    public string Email { get; set; }

    [ForeignKey("OrgCode")]
    public virtual Organisation Organisation { get; set; }

    [InverseProperty("ContactId")]
    public virtual IList<GroupToContactLink> GroupLinks { get; set; }
}

Are these inverse properties configured correctly?

Answer 1

Your problem is that the inverse property isn't the field on the GroupToContactLink class that references the Contact class.

[InverseProperty("ContactId")] // Wrong: don't use the field

But it is the navigation property on the class GroupToContactLink that references the Contact class.

[InverseProperty("Contact")] // Correct: use the navigation property