vercel/next.js · error · Error

It looks like you're trying to use TypeScript but do not hav

Error message

It looks like you're trying to use TypeScript but do not have the required package(s) installed.

Please install ${packagesHuman} by running:

	${install command} ${packagesCli}

If you are not trying to use TypeScript, please remove the tsconfig.json file from your package root (and any TypeScript files in your app and pages directories).

What it means

Thrown by missingDepsError() when Next.js detects a tsconfig.json (or .ts files) but the `typescript` (and/or related) package is not installed in node_modules. Next.js requires TypeScript as a peer/dev dependency to type-check and compile .ts routes; without it the build cannot proceed.

Source

Thrown at packages/next/src/lib/typescript/missingDependencyError.ts:23

import { getPkgManager } from '../helpers/get-pkg-manager'

export function missingDepsError(
  dir: string,
  missingPackages: MissingDependency[]
): never {
  const packagesHuman = getOxfordCommaList(missingPackages.map((p) => p.pkg))
  const packagesCli = missingPackages.map((p) => p.install ?? p.pkg).join(' ')
  const packageManager = getPkgManager(dir)

  const removalMsg =
    '\n\n' +
    bold(
      'If you are not trying to use TypeScript, please remove the ' +
        cyan('tsconfig.json') +
        ' file from your package root (and any TypeScript files in your app and pages directories).'
    )

  throw new Error(
    bold(
      red(
        `It looks like you're trying to use TypeScript but do not have the required package(s) installed.`
      )
    ) +
      '\n\n' +
      bold(`Please install ${bold(packagesHuman)} by running:`) +
      '\n\n' +
      `\t${bold(
        cyan(
          (packageManager === 'yarn'
            ? 'yarn add --dev'
            : packageManager === 'pnpm'
              ? 'pnpm install --save-dev'
              : 'npm install --save-dev') +
            ' ' +
            packagesCli
        )

View on GitHub (pinned to 0ae8c72462)

Solutions

Run the exact install command shown in the message (e.g. `npm install --save-dev typescript @types/react @types/node`).
If you did not intend to use TypeScript, delete tsconfig.json and any .ts/.tsx files in app/ and pages/ directories.
In a monorepo, ensure typescript resolves from the project root (check pnpm hoisting / yarn workspaces).

Example fix

// before: tsconfig.json exists but typescript not installed
// after: run
//   npm install --save-dev typescript @types/react @types/node @types/react-dom

Defensive patterns

Strategy: validation

Validate before calling

import { existsSync } from 'fs'
import { resolve } from 'path'
function ensureTypeScriptInstalled(projectDir: string) {
  if (!existsSync(resolve(projectDir, 'node_modules/typescript/package.json'))) {
    throw new Error('typescript is not installed. Run: npm install --save-dev typescript')
  }
}

Prevention

Keep typescript and @types/* in devDependencies.
Run `npm install` (including devDependencies) after cloning.
In monorepos, verify typescript resolves from the project root.
Remove tsconfig.json if you are not using TypeScript.

When it happens

Trigger: Project has a tsconfig.json or .tsx pages but `typescript` is absent from dependencies. Triggered by hasNecessaryDependencies during dev/build startup. The error lists the exact missing packages and the correct install command for your detected package manager (npm/yarn/pnpm).

Common situations: Cloning a repo and forgetting `npm install` for devDependencies; using a monorepo where typescript is hoisted incorrectly; deleting node_modules partially; starting from a JS template and adding .ts files without installing typescript.

Related errors

AI-assisted analysis of vercel/next.js@0ae8c72462 (2026-08-06). Data as JSON: /api/errors/5d09f9bc4660f95a. Report an issue: GitHub.