MarketDataStreamerV3 returns empty `ltpc` data and disconnects with 403

Developer API
1

Issue: MarketDataStreamerV3 returns empty ltpc data and disconnects with 403

I’m integrating Upstox MarketDataStreamerV3 (Node.js SDK) and consistently receiving empty ltpc objects even when the market is open and instruments are actively trading.

Environment

  • SDK: upstox-js-sdk
  • Mode: ltpc
  • Market: NSE_EQ
  • Instruments: RELIANCE, TCS, INFY
  • Market status: NORMAL_OPEN

Observed Behavior

  • WebSocket connects successfully
  • market_info events are received correctly
  • feeds payload contains empty ltpc objects:
{
  "feeds": {
    "NSE_EQ|RELIANCE": { "ltpc": {} },
    "NSE_EQ|TCS": { "ltpc": {} },
    "NSE_EQ|INFY": { "ltpc": {} }
  }
}


* After some time, the socket disconnects with:

Error: Unexpected server response: 403

What Works

  • REST LTP snapshot (/market-quote/ltp)
  • Historical candle data (V3)
  • Access token is valid and not expired

Questions

  1. Is ltpc strictly delta-only (emits only after a trade occurs)?
  2. Is a REST snapshot mandatory before subscribing to ltpc?
  3. What causes the 403 disconnect after a successful connection?
  4. Is full mode recommended over ltpc for live price display?

Any clarification or best-practice guidance would be appreciated.

Thanks.