deepseek-ai/deepseek-harness · error · TypeError

browser time zone must be canonical UTC or IANA Area/Locatio

Error message

browser time zone must be canonical UTC or IANA Area/Location: ${JSON.stringify(value)}

What it means

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

Source

Thrown at packages/context/time-context/src/request-zone.ts:26

/** Browser-zone facts derived from user-rpc messages in one open turn. */
export type BrowserTimeZoneContext =
  | { readonly kind: 'resolved'; readonly timeZone: string }
  | { readonly kind: 'mixed'; readonly timeZones: readonly string[] }
  | { readonly kind: 'missing' }

/** Read and validate a Host-canonicalized browser zone from one ordinary user-rpc message. */
function browserTimeZone(message: UserMessage): string | undefined {
  const source = message.source
  const value = source.kind === 'user'
    && 'rpcId' in source
    && 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.

View on GitHub (pinned to b150a551b8)

Solutions

1. Use UTC or a canonical IANA Area/Location time zone value.

When it happens

Trigger: Thrown at packages/context/time-context/src/request-zone.ts:26 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/a0b0010493d49865. Report an issue: GitHub.