mastra-ai/mastra · error

Unsupported JSON Schema target: "${options.target}". Support

Error message

Unsupported JSON Schema target: "${options.target}". Supported targets are: ${supportedTargets.join(', ')}

What it means

convertToJsonSchema in the zod-v3 standard-schema adapter maps an options.target (e.g. 'jsonSchema7', 'draft-2020-12') to a zod-to-json-schema target. If the target string is not in TARGET_MAP, it throws listing the supported targets, rather than emitting a schema for an unknown dialect.

Source

Thrown at packages/schema-compat/src/standard-schema/adapters/zod-v3.ts:40

 * Converts a Zod schema to JSON Schema using the specified target format.
 *
 * @param zodSchema - The Zod schema to convert
 * @param options - Standard Schema JSON options including the target format
 * @returns The JSON Schema representation
 * @throws Error if the target format is not supported
 *
 * @internal
 */
function convertToJsonSchema<T extends ZodType<any, ZodTypeDef, any>>(
  zodSchema: T,
  options: StandardJSONSchemaV1.Options,
): Record<string, unknown> {
  const target = TARGET_MAP[options.target];

  if (!target) {
    // For unknown targets, try to use jsonSchema7 as fallback or throw
    const supportedTargets = Object.keys(TARGET_MAP);
    throw new Error(
      `Unsupported JSON Schema target: "${options.target}". ` + `Supported targets are: ${supportedTargets.join(', ')}`,
    );
  }

  const jsonSchema = zodToJsonSchemaOriginal(zodSchema, {
    $refStrategy: 'none',
    target,
    override: (def: any) => {
      // Mark z.date() with x-date for downstream string→Date conversion.
      // Zod v3 has no z.coerce.date(), so all dates are strict.
      if (def.typeName === 'ZodDate') {
        return { type: 'string', format: 'date-time', 'x-date': true };
      }
      return ignoreOverride;
    },
  });

  traverse(jsonSchema, {

View on GitHub (pinned to 75dd419e61)

Solutions

1. Use one of the targets listed in the error message (e.g. the adapter's canonical 'jsonSchema7').
2. Check the TARGET_MAP keys in packages/schema-compat/src/standard-schema/adapters/zod-v3.ts for exact spellings.
3. Normalize/whitelist user- or config-supplied targets before calling the converter.
4. If you truly need an unsupported dialect, convert to the supported target and post-transform the schema.

Example fix

// before
convertToJsonSchema(schema, { target: 'draft-07' });
// after
convertToJsonSchema(schema, { target: 'jsonSchema7' });

const SUPPORTED_TARGETS = ['jsonSchema7', 'jsonSchema2019-09', 'openApi3_0']; // keep in sync with TARGET_MAP
function assertValidTarget(target: string) {
  if (!SUPPORTED_TARGETS.includes(target)) throw new TypeError(`Unsupported JSON Schema target: ${target}`);
}

type SupportedTarget = 'jsonSchema7' | 'jsonSchema2019-09' | 'openApi3_0';
function isSupportedTarget(t: string): t is SupportedTarget {
  return ['jsonSchema7', 'jsonSchema2019-09', 'openApi3_0'].includes(t);
}

try {
  js = convertToJsonSchema(schema, { target });
} catch (e) {
  if ((e as Error).message.includes('Unsupported JSON Schema target')) {
    js = convertToJsonSchema(schema, { target: 'jsonSchema7' });
  } else throw e;
}

When it happens

Trigger: Calling jsonSchemaConverter / convertToJsonSchema with an options.target value not in the adapter's TARGET_MAP — e.g. a typo like 'jsonschema7', a draft name like 'draft-07', or a target valid for another library but not this one.

Common situations: Copy-pasting target strings from other JSON-schema tooling; version changes where a target was renamed; config files where the target is user-supplied and unvalidated.

Related errors

• OBSERVABILITY_INVALID_CONFIG
• OBSERVABILITY_INVALID_INSTANCE_CONFIG
• We could not convert the schema to a JSONSchema
• ${message}
• Invalid parameters for ${strategy} strategy: '${keys}' not s

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/8084aa722a67f91c. Report an issue: GitHub.