vercel/turborepo · error · ConvertError

package_manager-unable_to_detect

package_manager-unable_to_detect

Error message

Could not determine package manager. Add `devEngines.packageManager` or legacy `packageManager` to `package.json`, or ensure a lockfile is present.

What it means

After confirming the directory exists, getWorkspaceDetails() iterates the MANAGERS map (npm, pnpm, yarn, bun, nub, aube, ...) running each detect() — lockfile presence and/or a declared package manager field. If none claims the workspace it throws ConvertError type package_manager-unable_to_detect with remediation hints in the message.

Source

Thrown at packages/turbo-workspaces/src/get-workspace-details.ts:30

    directory: root
  });
  if (!exists) {
    throw new ConvertError(
      `Could not find directory at ${workspaceRoot}. Ensure the directory exists.`,
      {
        type: "invalid_directory"
      }
    );
  }

  for (const { detect, read } of Object.values(MANAGERS)) {
    // eslint-disable-next-line no-await-in-loop -- we want to run serially and bail on the first success
    if (await detect({ workspaceRoot })) {
      return read({ workspaceRoot });
    }
  }

  throw new ConvertError(
    "Could not determine package manager. Add `devEngines.packageManager` or legacy `packageManager` to `package.json`, or ensure a lockfile is present.",
    {
      type: "package_manager-unable_to_detect"
    }
  );
}

View on GitHub (pinned to 9f94a7d215)

Solutions

Declare the manager in package.json: "packageManager": "pnpm@9.1.0" or "devEngines": { "packageManager": { "type": "npm", "version": "10.4.0" } }
Run one install with your manager so its lockfile exists, then retry
Restore the lockfile from git history if it was accidentally deleted

Example fix

// before: package.json has neither field, no lockfile on disk
{}

// after
{
  "packageManager": "pnpm@9.1.0"
}

Defensive patterns

Strategy: validation

Validate before calling

import { existsSync, readFileSync } from "node:fs";
import path from "node:path";

const lockfiles = ["package-lock.json", "pnpm-lock.yaml", "yarn.lock", "bun.lockb", "bun.lock"];
const root = path.resolve(dir);
const pkg = JSON.parse(readFileSync(path.join(root, "package.json"), "utf8"));
const declared = pkg?.devEngines?.packageManager ?? pkg?.packageManager;
const hasLockfile = lockfiles.some((f) => existsSync(path.join(root, f)));
if (!declared && !hasLockfile) {
  throw new Error("Declare a package manager or commit a lockfile before workspace detection");
}

Type guard

function isManagerUndetectedError(e: unknown): boolean {
  return e instanceof ConvertError && e.type === "package_manager-unable_to_detect";
}

Try / catch

try {
  await getWorkspaceDetails({ root });
} catch (e) {
  if (e instanceof ConvertError && e.type === "package_manager-unable_to_detect") {
    // prompt the user to pick a manager, write packageManager to package.json, retry
  } else throw e;
}

Prevention

Commit at least one lockfile and/or declare packageManager in package.json from day one
Don't gitignore lockfiles in application repos
Interactive tools should catch this error and offer to write the field for the user

When it happens

Trigger: A workspace with no recognized lockfile (package-lock.json, pnpm-lock.yaml, yarn.lock, bun.lockb/bun.lock, ...) and no devEngines.packageManager or legacy packageManager field in package.json.

Common situations: Fresh repo initialized but never installed; lockfile deleted or gitignored; obscure or internal managers (nub/aube) without their lockfiles present; package.json stripped by scaffolding.

Related errors

AI-assisted analysis of vercel/turborepo@9f94a7d215 (2026-08-16). Data as JSON: /api/errors/6f6cfa79ff3ab379. Report an issue: GitHub.