deepseek-ai/deepseek-harness · error · TypeError

browser time zone must be canonical: ${JSON.stringify(value)

Error message

browser time zone must be canonical: ${JSON.stringify(value)}

What it means

Error "browser time zone must be canonical: ${JSON.stringify(value)}" thrown in deepseek-ai/deepseek-harness.

Source

Thrown at packages/context/time-context/src/request-zone.ts:37

    && typeof source.rpcId === 'string'
    && 'clientTimeZone' in source
    && typeof source.clientTimeZone === 'string'
    ? source.clientTimeZone
    : undefined
  if (value === undefined) return undefined
  if (value !== 'UTC' && !IANA_TIME_ZONE.test(value)) {
    throw new TypeError(
      `browser time zone must be canonical UTC or IANA Area/Location: ${JSON.stringify(value)}`,
    )
  }
  let canonical: string
  try {
    canonical = new Intl.DateTimeFormat('en-US', { timeZone: value }).resolvedOptions().timeZone
  } catch (error: unknown) {
    throw new TypeError(`browser time zone is unsupported: ${JSON.stringify(value)}`, { cause: error })
  }
  if (canonical !== value) {
    throw new TypeError(`browser time zone must be canonical: ${JSON.stringify(value)}`)
  }
  return value
}

/**
 * Derive the unique, mixed, or missing browser zone for one open turn.
 * @param messages - Entered and proposed user messages belonging to the turn.
 * @returns Sorted, duplicate-free browser-zone facts.
 * @throws TypeError when a user-rpc source carries an invalid or noncanonical zone.
 */
export function deriveBrowserTimeZoneContext(
  messages: readonly UserMessage[],
): BrowserTimeZoneContext {
  const timeZones = [...new Set(messages.flatMap((message) => {
    const timeZone = browserTimeZone(message)
    return timeZone === undefined ? [] : [timeZone]
  }))].sort()
  const [timeZone, ...remaining] = timeZones

View on GitHub (pinned to b150a551b8)

Solutions

1. Use the canonical form of the time zone value.

When it happens

Trigger: Thrown at packages/context/time-context/src/request-zone.ts:37 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of deepseek-ai/deepseek-harness@b150a551b8 (2026-08-24). Data as JSON: /api/errors/c19a631cd1d13793. Report an issue: GitHub.