vercel/next.js · error · Error

Failed to resolve pattern "${patterns.join(',')}": ${error.m

Error message

Failed to resolve pattern "${patterns.join(',')}": ${error.message}

What it means

Thrown by resolveBuildPaths() when the underlying glob library rejects the combined include pattern while resolving build paths for the App/Pages routers. Next.js wraps the glob error to surface which pattern(s) failed so you can correct the path spec. It fires during build/dev startup when Next.js enumerates route files from user-supplied or default path patterns.

Source

Thrown at packages/next/src/lib/resolve-build-paths.ts:100

      : `{${includePatterns.join(',')}}`

  try {
    const matches = (await glob(combinedPattern, {
      cwd: projectDir,
      ignore: excludePatterns,
    })) as string[]

    if (matches.length === 0) {
      Log.warn(`Pattern "${patterns.join(',')}" did not match any files`)
    }

    for (const file of matches) {
      if (!fs.statSync(path.join(projectDir, file)).isDirectory()) {
        categorizeAndAddPath(file, appPaths, pagePaths, validFileMatcher)
      }
    }
  } catch (error) {
    throw new Error(
      `Failed to resolve pattern "${patterns.join(',')}": ${
        isError(error) ? error.message : String(error)
      }`
    )
  }

  return {
    appPaths: Array.from(appPaths).sort(),
    pagePaths: Array.from(pagePaths).sort(),
  }
}

/**
 * When the project keeps its `app/` or `pages/` directory under `src/`, prepend
 * `src/` to bare patterns so the glob actually matches files on disk. Patterns
 * that already include the `src/` prefix are returned unchanged.
 */
function addSrcPrefixIfNeeded(

View on GitHub (pinned to 0ae8c72462)

Solutions

Check the pattern printed in the message and validate it as a glob expression (balance braces, escape literal brackets/braces).
If using dynamic-route segments in the pattern, ensure they are well-formed ([slug], [...slug], [[...slug]]) so escapeBrackets can process them.
Reduce the pattern to a single include to isolate which entry breaks the combined {a,b} expansion.
Run a standalone glob (e.g. via the 'glob' package) against projectDir to reproduce the parser error outside Next.js.

Example fix

// before
resolveBuildPaths(['app/blog/[slug/page.tsx'], projectDir, pageExtensions)
// after (close the bracket)
resolveBuildPaths(['app/blog/[slug]/page.tsx'], projectDir, pageExtensions)

Defensive patterns

Strategy: validation

Validate before calling

import globOriginal from 'next/dist/compiled/glob'
import { promisify } from 'util'
const glob = promisify(globOriginal)

async function validatePattern(pattern, cwd) {
  try { await glob(pattern, { cwd }) }
  catch (e) { throw new Error(`Pattern '${pattern}' is invalid: ${e.message}`) }
}

Type guard

function isValidGlob(p: string): boolean {
  // basic brace/bracket balance check
  let braces = 0, brackets = 0
  for (const ch of p) {
    if (ch === '{') braces++
    if (ch === '}') braces--
    if (ch === '[') brackets++
    if (ch === ']') brackets--
    if (braces < 0 || brackets < 0) return false
  }
  return braces === 0 && brackets === 0
}

Try / catch

try {
  const paths = await resolveBuildPaths(patterns, projectDir, pageExtensions)
} catch (err) {
  if (err.message.startsWith('Failed to resolve pattern')) {
    // log pattern, fall back to default file discovery
  }
  throw err
}

Prevention

Validate glob patterns with a standalone glob call before passing to resolveBuildPaths.
Keep dynamic-route segments well-formed so escapeBrackets can process them.
Avoid hand-building brace-expanded combined patterns; pass individual patterns to the API.

When it happens

Trigger: Calling resolveBuildPaths() with a malformed glob pattern (e.g. unbalanced braces, invalid brace-expansion like '{a,b', or a pattern with illegal characters). Also triggered when escapeBrackets() or addSrcPrefixIfNeeded() produce a combined pattern that the compiled glob library cannot parse.

Common situations: A dynamic-route bracket pattern that was not escaped correctly, a typo in a comma-separated path list fed to the build, or an upgrade that changed how brace expansion is combined (the code joins multiple includes via {p1,p2}). Rare in normal projects; more likely in custom tooling or after editing app/pages directory structure.

Related errors

AI-assisted analysis of vercel/next.js@0ae8c72462 (2026-08-06). Data as JSON: /api/errors/d0cb673aa20fcb4b. Report an issue: GitHub.