vercel/next.js · error

TypeScript project references are not fully supported. Attem

Error message

TypeScript project references are not fully supported. Attempting to build in incremental mode.

What it means

runTypeCheck warns when the TypeScript config uses composite project references: Next.js type checking does not fully support build mode, so it falls back to running the check in incremental mode instead.

Source

Thrown at packages/next/src/lib/typescript/runTypeCheck.ts:133

    }
  }
  const requiredConfig = getRequiredConfiguration(typescript)

  const options = {
    ...requiredConfig,
    ...effectiveConfiguration.options,
    declarationMap: false,
    emitDeclarationOnly: false,
    noEmit: true,
  }

  let program:
    | import('typescript').Program
    | import('typescript').BuilderProgram
  let incremental = false
  if ((options.incremental || options.composite) && cacheDir) {
    if (options.composite) {
      warn(
        'TypeScript project references are not fully supported. Attempting to build in incremental mode.'
      )
    }
    incremental = true
    program = typescript.createIncrementalProgram({
      rootNames: fileNames,
      options: {
        ...options,
        composite: false,
        incremental: true,
        tsBuildInfoFile: path.join(cacheDir, '.tsbuildinfo'),
      },
    })
  } else {
    program = typescript.createProgram(fileNames, options)
  }

  const result = program.emit()

View on GitHub (pinned to 0eb3775416)

Solutions

1. Avoid TypeScript project references with Next.js, or accept incremental type-checking mode.

When it happens

Trigger: Thrown at packages/next/src/lib/typescript/runTypeCheck.ts:133 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/135eac4ac03bc685. Report an issue: GitHub.