400 Bad Request - Invalid Format

Message:
Property 'zip' was provided with an invalid value.
Or:
Invalid phone number format.

Cause:
Wrong data type or invalid formatting for a field (e.g., string instead of integer, incorrect date format, invalid email).

Fix:

  • Validate and sanitize data before sending.
  • Follow HubSpot’s data format requirements (e.g., ISO 8601 for dates).