vercel/next.js · error · Error

Failed to parse source map for

Error message

Failed to parse source map for ${filename}.

What it means

Wrapper in getSourceMapFromFile: the inline data: URI source map decoded successfully but JSON.parse rejected its contents. The parse error is attached as cause; the artifact embeds syntactically invalid JSON as its source map.

Solutions

1. Ensure the referenced source map is valid JSON; regenerate it with the bundler.

When it happens

Trigger: Parsing an inline or external source map fails.

Common situations: Corrupted source map data encountered while formatting dev error stacks.

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/7ba850b2d584fa95. Report an issue: GitHub.

Appendix: source

Thrown at packages/next/src/server/dev/get-source-map-from-file.ts:66

    try {
      buffer = dataUriToBuffer(sourceUrl)
    } catch (error) {
      throw new Error(`Failed to parse source map URL for ${filename}.`, {
        cause: error,
      })
    }

    if (buffer.type !== 'application/json') {
      throw new Error(
        `Unknown source map type for ${filename}: ${buffer.typeFull}.`
      )
    }

    try {
      return JSON.parse(buffer.toString())
    } catch (error) {
      throw new Error(`Failed to parse source map for ${filename}.`, {
        cause: error,
      })
    }
  }

  const sourceMapFilename = path.resolve(
    path.dirname(filename),
    decodeURIComponent(sourceUrl)
  )

  try {
    const sourceMapContents = await fs.readFile(sourceMapFilename, 'utf-8')

    return JSON.parse(sourceMapContents.toString())
  } catch (error) {
    throw new Error(`Failed to parse source map ${sourceMapFilename}.`, {
      cause: error,
    })

View on GitHub (pinned to 0eb3775416)