openai/codex · error · Error

outputSchema must be a plain JSON object

Error message

outputSchema must be a plain JSON object

What it means

Error "outputSchema must be a plain JSON object" thrown in openai/codex.

Source

Thrown at sdk/typescript/src/outputSchemaFile.ts:16

import { promises as fs } from "node:fs";
import os from "node:os";
import path from "node:path";

export type OutputSchemaFile = {
  schemaPath?: string;
  cleanup: () => Promise<void>;
};

export async function createOutputSchemaFile(schema: unknown): Promise<OutputSchemaFile> {
  if (schema === undefined) {
    return { cleanup: async () => {} };
  }

  if (!isJsonObject(schema)) {
    throw new Error("outputSchema must be a plain JSON object");
  }

  const schemaDir = await fs.mkdtemp(path.join(os.tmpdir(), "codex-output-schema-"));
  const schemaPath = path.join(schemaDir, "schema.json");
  const cleanup = async () => {
    try {
      await fs.rm(schemaDir, { recursive: true, force: true });
    } catch {
      // suppress
    }
  };

  try {
    await fs.writeFile(schemaPath, JSON.stringify(schema), "utf8");
    return { schemaPath, cleanup };
  } catch (error) {
    await cleanup();
    throw error;

View on GitHub (pinned to 339751715c)

Solutions

1. Pass outputSchema as a plain JSON object rather than an array or primitive.

When it happens

Trigger: Thrown at sdk/typescript/src/outputSchemaFile.ts:16 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of openai/codex@339751715c (2026-08-25). Data as JSON: /api/errors/48ec8bea97050170. Report an issue: GitHub.