Solana blockSubscribe 1009 error on WebSocket

When subscribing to large Solana blocks over WebSocket, you may encounter a 1009 error or a PayloadTooBig exception indicating that an incoming message exceeded the client’s maximum allowed size. This article explains:

1. What WebSocket close code 1009 means
2. How Python’s websockets library enforces a default limit
3. How NodeJS ws library handles message-size limits
4. Concrete fixes for both clients

1. What WebSocket close code 1009 means

Per the WebSocket RFC 6455, 1009 (MESSAGE_TOO_BIG) signals that an endpoint received a frame or message larger than it is willing or able to process. In practice:

• Python websockets lib throws a PayloadTooBig (then closes with code 1009).
• Node ws lib emits a 'close' event with code === 1009.

This is a protection against resource exhaustion or Denial-of-Service attacks.

2. Python “websockets” Default Limits

By default, the websockets library sets:

• max_size=2**20 bytes (1 MiB) per message
• max_queue=32 messages buffered

Any incoming frame > 1 MiB triggers:

websockets.exceptions.PayloadTooBig: over size limit (length > max_size)
ConnectionClosedError: sent 1009 (message too big)

3. Node.js “ws” Default Limits

The popular ws library defaults to:

• maxPayload=100 * 1024 * 1024 (100 MiB).

Although limit here is quite high, consider removing it completely.

4. Fixing the error

Python (asyncio websockets)

Increase or disable max_size in your connect() call:

import websockets

async with websockets.connect(
    ws_url,
    max_size=None           # disable limit, or set to a higher byte count
) as ws:
    …

• max_size=None ⇒ no limit
• max_size=10*1024*1024 ⇒ 10 MiB limit

Node.js (ws)

When instantiating the client, set maxPayload:

const WebSocket = require('ws');

const ws = new WebSocket(WS_ENDPOINT, {
  maxPayload: Infinity    // disable limit
  // or maxPayload: 10 * 1024 * 1024  // 10 MiB
});

• maxPayload: 0 or Infinity ⇒ no limit
• maxPayload: <bytes> ⇒ custom cap

If you still have questions or issues, feel free to reach out to our Support team by emailing support@chainstack.com or submitting this form.