dotnet/efcore · error · InvalidOperationException

The object '{name}' has been removed from the model.

Error message

The object '{name}' has been removed from the model.

What it means

An EntityTypeMappingFragment (the per-store-object mapping slice for an entity) tracks whether it is still attached to the model via its _builder field. Accessing the Builder after the fragment has been removed throws ObjectRemovedFromModel, signaling stale metadata use.

Source

Thrown at src/EFCore.Relational/Metadata/Internal/EntityTypeMappingFragment.cs:51

        ConfigurationSource configurationSource)
    {
        EntityType = entityType;
        StoreObject = storeObject;
        _configurationSource = configurationSource;
        _builder = new InternalEntityTypeMappingFragmentBuilder(this, ((IConventionModel)entityType.Model).Builder);
    }

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public virtual InternalEntityTypeMappingFragmentBuilder Builder
    {
        [DebuggerStepThrough]
        get => _builder
            ?? throw new InvalidOperationException(
                CoreStrings.ObjectRemovedFromModel(
                    StoreObject.DisplayName()));
    }

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that
    ///     doing so can result in application failures when updating to a new Entity Framework Core release.
    /// </summary>
    public virtual bool IsInModel
        => _builder is not null
            && ((IConventionAnnotatable)EntityType).IsInModel;

    /// <summary>
    ///     This is an internal API that supports the Entity Framework Core infrastructure and not subject to
    ///     the same compatibility standards as public APIs. It may be changed or removed without notice in
    ///     any release. You should only use it directly in your code with extreme caution and knowing that

View on GitHub (pinned to 3a2006ef56)

Solutions

1. Do not retain fragment references across model mutations; fetch them fresh from the current entity type after any model change.
2. Before accessing Builder, check fragment.IsInModel (which returns _builder is not null).
3. Reorder configuration so removals happen last and no later code touches removed fragments.

Example fix

// before
var fragment = entityType.FindMappingFragment(table);
modelBuilder.Entity<Order>().Ignore(...); // invalidates fragment
var b = fragment.Builder; // throws

// after
modelBuilder.Entity<Order>().Ignore(...);
var freshFragment = modelBuilder.Entity<Order>().Metadata.FindMappingFragment(table);
var b = freshFragment?.IsInModel == true ? freshFragment.Builder : null;

var fragment = entityType.FindMappingFragment(table);
if (fragment is { IsInModel: true } attached)
{
    var builder = attached.Builder;
}

static bool IsFragmentAttached(IReadOnlyEntityTypeMappingFragment f)
    => f is EntityTypeMappingFragment { IsInModel: true };

When it happens

Trigger: Holding a reference to a fragment returned by EntityType.MappingFragment or IReadOnlyEntityType.FindMappingFragment and then calling modelBuilder to remove it (or removing the entity/store object) before accessing its Builder.

Common situations: Conditional model building where a fragment is added then removed in a later pass; caching metadata objects across model rebuilds; using a fragment after EntityType.SetMappingFragment(null, ...).

Related errors

• The check constraint '{checkConstraint}' cannot be added to
• '{conflictingConfiguration}' cannot be set for '{property}'
• The DbFunction '{function}' has an invalid return type '{typ
• The DbFunction '{function}' is generic. Mapping generic meth
• The DbFunction '{function}' defined on type '{type}' must be

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/8e84b83148a0da57. Report an issue: GitHub.