remix-run/react-router · error · Error

Could not find package.json in ${rootDirectory} or any of it

Error message

Could not find package.json in ${rootDirectory} or any of its parent directories. Please add a package.json, or provide a custom entry.server.tsx/jsx file in your app directory.

What it means

Thrown during entry-server resolution when no custom entry.server file exists in the app directory AND findEntry cannot locate a package.json in rootDirectory or any parent (walkParents: true). React Router needs package.json both to choose the default entry.server (node vs web) and to ensure the isbot dependency is present; without it, defaulting cannot proceed safely. The message suggests either adding a package.json or providing a custom app/entry.server.tsx/jsx.

Source

Thrown at packages/react-router-dev/config/config.ts:1047

  );

  let userEntryClientFile = findEntry(appDirectory, "entry.client");
  let userEntryServerFile = findEntry(appDirectory, "entry.server");

  let entryServerFile: string;
  let entryClientFile = userEntryClientFile || "entry.client.tsx";

  if (userEntryServerFile) {
    entryServerFile = userEntryServerFile;
  } else {
    let packageJsonPath = findEntry(rootDirectory, "package", {
      extensions: [".json"],
      absolute: true,
      walkParents: true,
    });

    if (!packageJsonPath) {
      throw new Error(
        `Could not find package.json in ${rootDirectory} or any of its parent directories. Please add a package.json, or provide a custom entry.server.tsx/jsx file in your app directory.`,
      );
    }

    let packageJsonDirectory = Path.dirname(packageJsonPath);
    let pkgJson = await readPackageJSON(packageJsonDirectory);
    let deps = pkgJson.dependencies ?? {};

    if (!deps["isbot"]) {
      console.log(
        "adding `isbot@5` to your package.json, you should commit this change",
      );

      await updatePackage(packageJsonPath, (pkg) => {
        pkg.dependencies ??= {};
        pkg.dependencies.isbot = "^5";
        sortPackage(pkg);
      });

View on GitHub (pinned to 1fd704a7da)

Solutions

Ensure a package.json exists at or above the project root (npm init -y in the project directory).
Run react-router build from the directory that contains package.json.
Add a custom app/entry.server.tsx (or .jsx) so the default-resolution path that needs package.json is skipped.
If in a monorepo, confirm the tool resolves the workspace root that contains package.json; check rootDirectory in react-router.config.ts.
Reinstall dependencies (npm install) so isbot and other deps are present after adding package.json.

Example fix

// before -- project dir has no package.json and no custom entry server
react-router build
// after -- add package.json (or add app/entry.server.tsx)
npm init -y && npm install && react-router build
// alternative: create app/entry.server.tsx to bypass default resolution

Defensive patterns

Strategy: validation

Validate before calling

import fs from 'node:fs';
import path from 'node:path';
function hasPackageJsonUpTree(start: string): boolean {
  let dir = start;
  while (true) {
    if (fs.existsSync(path.join(dir, 'package.json'))) return true;
    const parent = path.dirname(dir);
    if (parent === dir) return false;
    dir = parent;
  }
}
// if (!hasPackageJsonUpTree(rootDirectory)) -> create package.json or add app/entry.server.tsx

Prevention

Always scaffold with a package.json at the project root (npm init -y).
Run react-router build from the directory containing package.json.
Provide a custom app/entry.server.tsx if you intentionally have no package.json.
In monorepos, double-check rootDirectory/appDirectory in react-router.config.ts.

When it happens

Trigger: Running react-router build/dev in a directory that has no package.json anywhere up the tree (e.g. scaffolding files by hand, or pointing the tool at a bare subfolder); the project root was misconfigured; package.json was deleted or never created; running inside a sandbox that excludes the parent package.json.

Common situations: Standalone experiment folders without package.json; an incorrectly set rootDirectory/appDirectory; monorepo where the tool was invoked from a directory above the package; filesystem permission issue hiding package.json.

Related errors

AI-assisted analysis of remix-run/react-router@1fd704a7da (2026-08-12). Data as JSON: /api/errors/43fced40773cdd45. Report an issue: GitHub.