neoclide/coc.nvim · error

maxResponseSize must be a positive finite number

Error message

maxResponseSize must be a positive finite number

What it means

resolveRequestOptions in src/model/fetch.ts applies a response-size cap to every request, defaulting to DEFAULT_MAX_RESPONSE_SIZE when options.maxResponseSize is undefined. If the provided value is not a positive finite number (0, negative, NaN, Infinity), it throws this error before the request is made, protecting against unbounded memory use when buffering responses.

Source

Thrown at src/model/fetch.ts:192

    headers: {
      'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64)',
      'Accept-Encoding': 'gzip, deflate',
      ...(options.headers ?? {})
    }
  }
  if (dataType == 'object') {
    opts.headers['Content-Type'] = 'application/json'
  } else if (dataType == 'string') {
    opts.headers['Content-Type'] = 'text/plain'
  }
  if (proxyOptions.proxyAuthorization) opts.headers['Proxy-Authorization'] = proxyOptions.proxyAuthorization
  if (proxyOptions.proxyCA) opts.ca = fs.readFileSync(proxyOptions.proxyCA)
  if (options.user) opts.auth = options.user + ':' + (toText(options.password))
  if (url.username) opts.auth = url.username + ':' + (toText(url.password))
  if (options.timeout) opts.timeout = options.timeout
  if (options.buffer) opts.buffer = true
  let maxResponseSize = options.maxResponseSize ?? DEFAULT_MAX_RESPONSE_SIZE
  if (!Number.isFinite(maxResponseSize) || maxResponseSize <= 0) throw new Error('maxResponseSize must be a positive finite number')
  opts.maxResponseSize = maxResponseSize
  return opts
}

/**
 * Extract and validate the charset parameter of a Content-Type header.
 * Handles quoted values (charset="utf-8") and trailing parameters
 * (charset=utf-8; format=flowed); throws for unsupported encodings.
 */
function parseCharset(contentType: string): BufferEncoding {
  let match = /;\s*charset\s*=\s*"?([^";\s]+)"?/i.exec(contentType)
  let encoding = match ? match[1] : 'utf8'
  let lower = encoding.toLowerCase()
  if (lower === 'iso-8859-1' || lower === 'latin-1') encoding = 'latin1'
  else if (lower === 'utf-16' || lower === 'utf-16le' || lower === 'ucs-2' || lower === 'ucs2') encoding = 'utf16le'
  else if (lower === 'us-ascii') encoding = 'ascii'
  if (!Buffer.isEncoding(encoding)) {
    throw new Error(`Unsupported charset: ${encoding}`)

View on GitHub (pinned to 50e974d969)

Solutions

1. Pass a positive finite number of bytes, e.g. maxResponseSize: 10 * 1024 * 1024.
2. Omit maxResponseSize to use the library default instead of 0 for 'unlimited'.
3. Coerce config values: const n = Number(v); if (Number.isFinite(n) && n > 0) use n.

Example fix

// before
fetch(url, { maxResponseSize: 0 })
// after
fetch(url, { maxResponseSize: 50 * 1024 * 1024 }) // or omit the option

function validMaxResponseSize(v) {
  if (v === undefined) return true
  return Number.isFinite(v) && v > 0
}
if (!validMaxResponseSize(opts.maxResponseSize))
  throw new Error('maxResponseSize must be a positive finite number or undefined')

function isPositiveFinite(v: unknown): v is number { return typeof v === 'number' && Number.isFinite(v) && v > 0 }

try {
  return await fetch(url, { maxResponseSize })
} catch (e) {
  if (/maxResponseSize must be/.test(e.message)) return fetch(url) // fall back to default limit
  throw e
}

When it happens

Trigger: Calling fetch() with maxResponseSize: 0 intending 'unlimited', maxResponseSize: -1, or a NaN/Infinity value computed from config; passing a string from an env var without Number() conversion.

Common situations: Users setting 0 or -1 as 'no limit' sentinels in coc settings; config parsers returning strings; arithmetic on undefined producing NaN.

Understand the failure class

Background: Invalid option value errors: "must be one of", "is not a valid", and "only allows" failures explained — this error's family across 23 libraries.

Related errors

• Invalid action ${action}
• ${name} must be a positive finite number
• Not valid protocol with ${urlInput}, should be http: or http
• name and doComplete required for createSource
• Required root pattern not resolved.

AI-assisted analysis of neoclide/coc.nvim@50e974d969 (2026-08-31). Data as JSON: /api/errors/fedae4493df0e263. Report an issue: GitHub.