invalid_date 🔌 API

API Error: Invalid date format — expected ISO 8601 (YYYY-MM-DDTHH:mm:ssZ)

A date or timestamp in the request isn’t in the format the API expects — usually ISO 8601 with a time zone, or a Unix timestamp.

Seen on: REST API

Meaning

Dates are a classic source of 400/422 errors. Locale formats like 03/10/2026 are ambiguous, “2026-10-03 14:00” lacks the T separator and time zone, and some APIs want seconds since epoch while others want milliseconds or an RFC 3339 string.

Validators say things like “must match format "date-time"”, “Invalid datetime”, “Input should be a valid datetime” (Pydantic) or “Cannot deserialize value of type LocalDateTime” (Jackson).

Common causes

  • Locale-formatted string (dd/mm/yyyy, mm/dd/yyyy)
  • Missing T separator or time zone/offset
  • Milliseconds sent where the API expects seconds (or vice versa)
  • Date object serialized in a non-standard way
  • Invalid offset like +5:30 instead of +05:30

⚡ Quick fix

  1. Send ISO 8601/RFC 3339 strings in UTC: 2026-10-03T14:00:00Z
  2. Use toISOString() / isoformat() instead of formatting by hand
  3. Check whether the API wants seconds or milliseconds

Detailed fix by platform

Node.js

  1. javascript
    const body = { start: new Date(start).toISOString() };          // 2026-10-03T14:00:00.000Z
const unix = Math.floor(Date.now() / 1000);                        // seconds, not ms

Python

  1. python
    from datetime import datetime, timezone
datetime.now(timezone.utc).isoformat()   # '2026-10-03T14:00:00+00:00'

How to diagnose

  1. Raw value — Exact string sent
  2. Docs — ISO string, date-only, seconds or ms?
  3. Time zone — Present and well-formed?

🧠 Still stuck? Analyze your error

Paste the full message, response headers or stack trace — we'll detect the platform and point to the most likely cause.