vercel/next.js · error · Error

Failed to parse JSON body of ${filePath}: ${(err as Error).m

Error message

Failed to parse JSON body of ${filePath}: ${(err as Error).message}

What it means

Parse failure in parseClientReferenceManifest: it extracts the first balanced {...} JSON object from a generated client reference manifest file and JSON.parse rejected that slice. The original parser message is chained in, so this indicates a corrupted or unexpectedly formatted build artifact at filePath.

Source

Thrown at packages/next/src/cli/internal/static-routes-info.ts:516

        escape = true
      } else if (ch === quote) {
        inString = false
      }
      continue
    }
    if (ch === '"' || ch === "'") {
      inString = true
      quote = ch
    } else if (ch === '{') {
      depth++
    } else if (ch === '}') {
      depth--
      if (depth === 0) {
        const body = content.slice(start, i + 1)
        try {
          return JSON.parse(body)
        } catch (err) {
          throw new Error(
            `Failed to parse JSON body of ${filePath}: ${(err as Error).message}`
          )
        }
      }
    }
  }
  throw new Error(`Unterminated JSON object in ${filePath}.`)
}

/**
 * Add a chunk path to the right client-side category. Strips a `?dpl=...`
 * (or any other) query suffix that webpack appends, then dispatches by
 * extension. Returns true if the path looked like a real asset (had an
 * extension we recognize) — used by the webpack `clientModules` walker
 * below to filter out chunk IDs.
 */
function addClientChunk(rawPath: string, sets: FileSets): boolean {
  // Some manifests append `?dpl=ID` to chunk URLs.

View on GitHub (pinned to 0eb3775416)

Solutions

Fix the JSON syntax in the referenced routes info file, or delete it so Next.js regenerates it.

Defensive patterns

Strategy: try-catch

When it happens

Trigger: Reading a JSON metadata file for static routes info fails JSON parsing.

Common situations: A corrupted or hand-edited routes-manifest or similar JSON file in .next cannot be parsed.

Understand the failure class

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

AI-assisted analysis of vercel/next.js@0eb3775416 (2026-08-19). Data as JSON: /api/errors/16b3f283f123a072. Report an issue: GitHub.