dotnet/efcore · error · InvalidOperationException

The property ' ' on type ' ' is mapped to a JSON entity and…

Error message

The property '{property}' on type '{type}' is mapped to a JSON entity and cannot be configured as not auto-loaded. JSON-mapped entities are always loaded as a unit.

What it means

RelationalModelValidator.ValidateAutoLoaded throws AutoLoadedJsonProperty when a property on a JSON-mapped entity type is configured as IsAutoLoaded(false). JSON entities are serialized/deserialized as a single unit, so individual properties cannot opt out of being loaded — the validator enforces this invariant at model finalization.

Solutions

Remove IsAutoLoaded(false) from any property on a JSON-mapped entity type — the whole JSON document is always loaded.
If granular loading is required, do not map the entity to JSON; flatten to columns or split into a separate non-JSON entity.
Project only the needed fields in queries (Select) instead of trying to opt out at the model level.

Example fix

// before
modelBuilder.Entity<Order>()
    .OwnsOne(o => o.Details, d =>
    {
        d.ToJson("details");
        d.Property(p => p.BigNotes).IsAutoLoaded(false); // throws
    });

// after — drop the IsAutoLoaded call; project instead if needed
modelBuilder.Entity<Order>()
    .OwnsOne(o => o.Details, d => d.ToJson("details"));

Defensive patterns

Strategy: validation

Validate before calling

foreach (var p in entityType.GetProperties())
    if (entityType.IsMappedToJson() && !p.IsAutoLoaded)
        throw new InvalidOperationException($"Property {p.Name} on JSON entity cannot be non-auto-loaded.");

Type guard

static bool IsJsonPropertyOnJsonEntity(IProperty p) => p.DeclaringType.IsMappedToJson();

Prevention

Do not call IsAutoLoaded(false) on properties of JSON-mapped entities.
When migrating owned types to ToJson, audit and remove prior AutoLoaded(false) calls.
Use query projection (Select) to limit fields read from JSON instead of model-level opt-out.

When it happens

Trigger: Calling property.IsAutoLoaded = false (or IsAutoLoaded(ConfigurationSource.Explicit).AutoLoaded(false)) on a property whose declaring entity type is mapped to JSON (entity.IsMappedToJson() is true via ToJson). The base validator allows it; the relational override adds the JSON check and throws.

Common situations: Configuring an owned JSON entity and trying to mark a large text property as lazy/non-auto-loaded to save bandwidth; migrating an owned-type configuration to ToJson and forgetting to remove the AutoLoaded(false) calls; bulk-applying AutoLoaded conventions to all properties including JSON ones.

Related errors

AI-assisted analysis of dotnet/efcore@3a2006ef56 (2026-08-11). Data as JSON: /api/errors/008a70b08addcf8c. Report an issue: GitHub.

Appendix: source

Thrown at src/EFCore.Relational/Infrastructure/RelationalModelValidator.cs:211

                ValidatePropertyOverride(property, storeObjectOverride, logger);
            }
        }

        ValidateBoolWithDefaults(property, logger);
    }

    /// <inheritdoc />
    protected override void ValidateAutoLoaded(
        IProperty property,
        ITypeBase structuralType,
        IDiagnosticsLogger<DbLoggerCategory.Model.Validation> logger)
    {
        base.ValidateAutoLoaded(property, structuralType, logger);

        if (!property.IsAutoLoaded
            && structuralType.IsMappedToJson())
        {
            throw new InvalidOperationException(
                RelationalStrings.AutoLoadedJsonProperty(property.Name, structuralType.DisplayName()));
        }
    }

    /// <inheritdoc />
    protected override void ValidateKey(
        IKey key,
        IDiagnosticsLogger<DbLoggerCategory.Model.Validation> logger)
    {
        base.ValidateKey(key, logger);

        foreach (var property in key.Properties)
        {
            if (property.DeclaringType is IComplexType complexType
                && complexType.IsMappedToJson())
            {
                throw new InvalidOperationException(
                    RelationalStrings.KeyPropertyInJsonComplexType(

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