Verified Developer Solution • 100% OfflineFix "data must NOT have additional properties" in JSON Schema
Learn how to resolve strict validation errors in JSON Schema when payloads contain undocumented fields.
The Problem (Error Root Cause)Exception
Your payload validation fails with "data must NOT have additional properties". Your schema enforces `additionalProperties: false`, but the JSON being sent contains extra fields.
Identified via runtime validation & stack traces
The Solution (Step-by-Step Fix)Verified
Either remove the extra fields from your JSON payload or set `additionalProperties: true` in your schema definition to allow fields that aren't explicitly defined.
Deterministic, non-destructive resolution
Code Standard: Bad Pattern vs Verified Fix
Live SyntaxAnti-Pattern vs Verified Fix
1// ❌ Bad: Strict schema rejects extra field2"additionalProperties": false3{ "name": "John", "extra": "data" } // Fails validation4 5// ✅ Good: Allow extra fields6"additionalProperties": trueTest and resolve this using JSON Schema Validator
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Frequently Asked Questions
Q:Is additionalProperties: false secure?
Yes, it ensures your application only processes expected data and prevents over-posting attacks.
Q:How do I test this schema?
Use our JSON Schema Validator to instantly check if your JSON data violates this property.