vercel/next.js · error

Invalid casing detected for project dir, received ${resolved

Error message

Invalid casing detected for project dir, received ${resolvedDir} actual path ${realDir}, see more info here https://nextjs.org/docs/messages/invalid-project-dir-casing

What it means

Error "Invalid casing detected for project dir, received ${resolvedDir} actual path ${realDir}, see more info here https://nextjs.org/docs/messages/invalid-project-dir-casing" thrown in vercel/next.js.

Source

Thrown at packages/next/src/lib/get-project-dir.ts:16

import path from 'path'
import { warn } from '../build/output/log'
import { detectTypo } from './detect-typo'
import { realpathSync } from './realpath'
import { printAndExit } from '../server/lib/utils'

export function getProjectDir(dir?: string, exitOnEnoent = true) {
  const resolvedDir = path.resolve(dir || '.')
  try {
    const realDir = realpathSync(resolvedDir)

    if (
      resolvedDir !== realDir &&
      resolvedDir.toLowerCase() === realDir.toLowerCase()
    ) {
      warn(
        `Invalid casing detected for project dir, received ${resolvedDir} actual path ${realDir}, see more info here https://nextjs.org/docs/messages/invalid-project-dir-casing`
      )
    }

    return realDir
  } catch (err: any) {
    if (err.code === 'ENOENT' && exitOnEnoent) {
      if (typeof dir === 'string') {
        const detectedTypo = detectTypo(dir, [
          'build',
          'dev',
          'info',
          'lint',
          'start',
          'telemetry',
          'experimental-test',
        ])

View on GitHub (pinned to 0eb3775416)

Solutions

1. Run the command from the directory using the exact on-disk casing of the project path.

When it happens

Trigger: Thrown at packages/next/src/lib/get-project-dir.ts:16 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of vercel/next.js@0eb3775416 (2026-08-19). Data as JSON: /api/errors/63c6991839bb1367. Report an issue: GitHub.