colinhacks/zod · error · Error

unevaluatedProperties is not supported

Error message

unevaluatedProperties is not supported

What it means

Thrown by convertBaseSchema when the input contains `unevaluatedProperties`. Like unevaluatedItems, this keyword only has meaning relative to evaluated applicators and cannot be statically lowered into Zod's object/record/catchall model.

Source

Thrown at packages/zod/src/v4/classic/from-json-schema.ts:159

  }

  throw new Error(`Reference not found: ${ref}`);
}

function convertBaseSchema(schema: JSONSchema.JSONSchema, ctx: ConversionContext): ZodType {
  // Handle unsupported features
  if (schema.not !== undefined) {
    // Special case: { not: {} } represents never
    if (typeof schema.not === "object" && Object.keys(schema.not).length === 0) {
      return z.never();
    }
    throw new Error("not is not supported in Zod (except { not: {} } for never)");
  }
  if (schema.unevaluatedItems !== undefined) {
    throw new Error("unevaluatedItems is not supported");
  }
  if (schema.unevaluatedProperties !== undefined) {
    throw new Error("unevaluatedProperties is not supported");
  }
  if (schema.if !== undefined || schema.then !== undefined || schema.else !== undefined) {
    throw new Error("Conditional schemas (if/then/else) are not supported");
  }
  if (schema.dependentSchemas !== undefined || schema.dependentRequired !== undefined) {
    throw new Error("dependentSchemas and dependentRequired are not supported");
  }

  // Handle $ref
  if (schema.$ref) {
    const refPath = schema.$ref;
    if (ctx.refs.has(refPath)) {
      return ctx.refs.get(refPath)!;
    }

    if (ctx.processing.has(refPath)) {
      // Circular reference - use lazy
      return z.lazy(() => {

View on GitHub (pinned to 912f0f51b0)

Solutions

1. Drop `unevaluatedProperties` and rely on `additionalProperties: false` (which the converter supports as `.strict()`).
2. Inline composed schemas so all properties are visible to the object converter, then use `additionalProperties: false`.
3. Strip the keyword in a pre-pass if your use case tolerates the looser behaviour.

Example fix

// before
{ "allOf": [{ ... }], "unevaluatedProperties": false }

// after
{ "type": "object", "properties": { ... }, "additionalProperties": false }

function stripUnsupported(schema: any) {
  if (schema.unevaluatedProperties !== undefined) {
    delete schema.unevaluatedProperties;
  }
}

function hasUnevaluatedProperties(s: any): boolean { return s?.unevaluatedProperties !== undefined; }

When it happens

Trigger: Schemas using `unevaluatedProperties: false` (typically to forbid any property not explicitly validated, including those surfaced via allOf/$ref).

Common situations: Strict-mode JSON Schemas from API style guides; auto-generated schemas from TypeScript types with `additionalProperties: false` plus composition; draft-2020-12 strict profiles.

Related errors

• not is not supported in Zod (except { not: {} } for never)
• unevaluatedItems is not supported
• Conditional schemas (if/then/else) are not supported
• dependentSchemas and dependentRequired are not supported
• Unsupported type: ${type}

AI-assisted analysis of colinhacks/zod@912f0f51b0 (2026-08-03). Data as JSON: /data/errors/feda1447c554dd47.json. Report an issue: GitHub.