FasterXML/jackson-databind · error · UnsupportedOperationException

Instances of should not get visited

Error message

Instances of {} should not get visited

What it means

Thrown by BeanProperty.Std.depositSchemaProperty() (an internal placeholder BeanProperty implementation) when it is inadvertently visited during JSON schema generation. The Std implementation is a minimal stand-in meant only to carry property metadata for contextual deserializer/serializer lookup; it intentionally cannot emit schema properties. If schema generation reaches this object, it indicates an internal wiring path that was never expected to execute.

Solutions

1. Override depositSchemaProperty() in your custom serializer/property writer to be a no-op or to delegate to a real property instead of using BeanProperty.Std.
2. Construct the BeanProperty with a concrete AnnotatedMember so the schema visitor has a real member to introspect.
3. Avoid passing BeanProperty.Std instances into BeanPropertyWriter constructors that participate in schema generation.

Example fix

// before
BeanProperty prop = new BeanProperty.Std(name, type, wrapperName, member);
// after: provide a full implementation or skip schema visit
BeanProperty prop = new BeanProperty.Std(name, type, wrapperName, member) {
    @Override
    public void depositSchemaProperty(JsonObjectFormatVisitor v, SerializationContext c) {
        // no-op: this property does not contribute to schema
    }
};

// Before schema generation, check if the property is a placeholder
if (property instanceof BeanProperty.Std) {
    // skip or replace with a real property before visiting
    return;
}

boolean isVisitableBeanProperty(BeanProperty p) {
    return !(p instanceof BeanProperty.Std);
}

When it happens

Trigger: Calling ObjectMapper.acceptJsonFormatVisitor() or generating a JSON Schema on a type whose serializer/property writer contains a BeanProperty.Std instance. This typically happens when a custom ValueSerializer or ValueDeserializerModifier constructs a BeanProperty.Std and registers it on a BeanPropertyWriter that then gets traversed by the format visitor.

Common situations: Custom serializers that reuse BeanProperty.Std as the property marker for properties that later get visited by schema generation. Also seen when third-party Jackson modules create writers without a real AnnotatedMember backing them.

Related errors

• AnnotationIntrospector.
• Property ' ' already had index ( ), trying to assign

AI-assisted analysis of FasterXML/jackson-databind@87876ca5c0 (2026-08-11). Data as JSON: /api/errors/9d471b358ed7d6ec. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/tools/jackson/databind/BeanProperty.java:279

        @Override public JavaType getType() { return _type; }
        @Override public PropertyName getWrapperName() { return _wrapperName; }
        @Override public boolean isRequired() { return _metadata.isRequired(); }
        @Override public PropertyMetadata getMetadata() { return _metadata; }
        @Override public AnnotatedMember getMember() { return _member; }

        @Override
        public boolean isVirtual() { return false; }

        /**
         * Implementation of this method throws
         * {@link UnsupportedOperationException}, since instances of this
         * implementation should not be used as part of actual structure
         * visited. Rather, other implementations should handle it.
         */
        @Override
        public void depositSchemaProperty(JsonObjectFormatVisitor objectVisitor,
                SerializationContext ctxt) {
            throw new UnsupportedOperationException("Instances of "+getClass().getName()+" should not get visited");
        }
    }

    /**
     * Alternative "Null" implementation that can be used in cases where a non-null
     * {@link BeanProperty} is needed
     */
    public static class Bogus implements BeanProperty
    {
        @Override
        public String getName() {
            return "";
        }

        @Override
        public PropertyName getFullName() {
            return PropertyName.NO_NAME;
        }

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