oven-sh/bun · error · Error

Invalid data object: ${JSON.stringify(data)}

Error message

Invalid data object: ${JSON.stringify(data)}

What it means

The lockfile's format/version is newer than this Bun understands. For binary bun.lockb: format > FormatVersion::current() (src/install/lockfile/bun.lockb.rs:411-412). During migration it fires for unsupported npm package-lock.json lockfileVersions (src/install/migration.rs:269-278, which suggests regenerating with `npm install --package-lock-only --lockfile-version=3`) and for too-new pnpm lockfile versions (migration.rs:106-115).

Source

Thrown at bench/postMessage/postMessage-object.mjs:60

        case ${objects.small.property.length}:
        case ${objects.medium.property.length}:
        case ${objects.large.property.length}: {
          if (
            data.a === "a!" && 
            data.b === "b!" && 
            data.second === "c!" && 
            data.bool === true && 
            data.nully === null && 
            data.undef === undefined && 
            data.int === 0 && 
            data.double === 1.234 && 
            data.falsy === false) {
            Atomics.add(int, 0, 1);
            break;    
          }
        }
        default: {
          throw new Error("Invalid data object: " + JSON.stringify(data));
        }
      }
      
    });
  `;

  worker = new Worker(workerCode, { eval: true, workerData: receivedCount });

  worker.on("message", confirmationId => {});

  worker.on("error", error => {
    console.error("Worker error:", error);
  });
}

// Initialize worker before running benchmarks
createWorker();

View on GitHub (pinned to 8c5296ac45)

Solutions

1. Upgrade Bun to at least the version that wrote the lockfile (`bun upgrade` or reinstall)
2. For package-lock.json migration, regenerate at v3: `npm install --package-lock-only --lockfile-version=3`
3. Or delete the lockfile and let your current Bun re-resolve
4. Pin a team-wide Bun version via package.json `packageManager` / engines and CI images

Example fix

# before: older Bun + newer lockfile
$ bun install
error: Unexpected lockfile version

# after
$ bun upgrade && bun install

import { existsSync } from "node:fs";
function lockfileVersionSupported() {
  if (existsSync("package-lock.json")) {
    const v = require("./package-lock.json").lockfileVersion;
    return v === 3; // Bun migrates lockfileVersion 3 only
  }
  return true; // bun.lock/bun.lockb: upgrade Bun instead
}

const isSupportedPackageLock = (lock) => typeof lock?.lockfileVersion === "number" && lock.lockfileVersion === 3;

When it happens

Trigger: A teammate or CI running a newer Bun committed bun.lockb/bun.lock; migrating a package-lock.json at v1/v2; a pnpm-lock.yaml written by a newer pnpm than Bun's migrator supports.

Common situations: Mixed Bun versions across a team or between local machine and CI; picking up a repo after the lockfile was upgraded elsewhere.

Related errors

• Expected ${receivedCount[0]} to equal ${sentCount}
• size mismatch
• not 200
• picsum ${p.id}: ${res.status}
• Expected ${receivedCount[0]} to equal ${sentCount}

AI-assisted analysis of oven-sh/bun@8c5296ac45 (2026-08-16). Data as JSON: /api/errors/d251e48057b20693. Report an issue: GitHub.