WebSocket Error Codes

These numbers arrive in WS JSON: {"code":5xx,"msg":"...","trace":"..."}. Subscribe rejections are the exception — they arrive prefixed with Subscribe fail: plus one space, and are not bare JSON — see the next section.

Do not interpret them with the REST ret table. REST 508 means the symbol is missing; WS 508 means the API key expired. REST: REST API Error Codes. Limits: WebSocket Limitation.

Subscribe acks 10001 / 10004 / 10007 with msg=ok only mean the frame was accepted. A wrong business for the symbol can still ack and then never push.

The welcome frame {"code":200,"msg":"ws connect success"} is not an error. business=stock may also send a plaintext greeting first.

Subscribe rejections: prefixed, not bare JSON

When a subscribe is rejected, the server replies with a text frame that starts with Subscribe fail: followed by one space. Running JSON.parse / json.loads on the whole frame throws. If your code silently drops frames it cannot parse, the symptom is "connected, subscribe sent, but no market data and no error at all".

There are four shapes. The first two carry JSON after the prefix; the last two carry plain English text and no code:

Condition	Frame
Symbols on this connection exceed the limit (505)	Subscribe fail: {"traceId":"...","code":505,"msg":"Single WS subscribe exceeds the limit 200"}
Total symbols across connections exceed the limit (516)	Subscribe fail: {"traceId":"...","code":516,"msg":"All WS subscribe exceeds the limit 6000"}
business does not match the symbol type	Subscribe fail: Some product is not stock product like:BTCUSDT.Business stock can only subscribe stock products
Market not included in your plan	Subscribe fail: No access to the following market data:JP

In the two JSON shapes the field is traceId, not the trace used by other frames.

Recommended handling:

1. Check whether the text starts with Subscribe fail:; if so, strip that prefix together with the space after it.

2. If the remainder starts with {, parse it as JSON and read code against the table below. Otherwise pass the whole remainder up as the error message.

3. Do not resend the same subscribe as-is. Wrong business, missing market entitlement and 505 fail identically no matter how many times you retry. 516 may be retried with backoff, but retry frames also count against the 60 requests per minute budget (see WebSocket Limitation) — unthrottled resends trigger 501, the server closes the connection, the client reconnects, hits the limit again, and loops.

Application codes

code	Meaning	English msg
200	Connected (welcome)	ws connect success
500	Server error	server error
501	Per-minute request limit (includes heartbeats, 60/min)	Request frequency exceed the limit：%s times per minute
502	Daily request limit	Request frequency for the day upper limit：%s
503	Candlestick count exceeds the limit	Kline quantity exceeds the limit：%s
504	Order-book depth exceeds the limit	Orderbook depth exceeds the limit：%s
505	Symbols on this connection exceed the limit	Single WS subscribe exceeds the limit %s
506	Parameter error	Param error：%s
507	Required parameter missing	Param lost：%s
508	API key permission expired	The apiKey permission has expired
509	API key invalid	The apiKey is invalid
510	API key empty	The apiKey is empty
511	API key blacklisted	The apiKey is in the blacklist
512	WebSocket connection count exceeds the plan	WebSocket connections exceeds the limit：%s
513	Heartbeat timeout	Websocket heartbeat timeout
514	Wrong WebSocket URL	Websocket Url Wrong
515	Payload is not JSON	Param not json，request failed
516	Total symbols across connections exceed the limit	All WS subscribe exceeds the limit %s

There is no 427. Connection-over-quota is 512.

Handshake extras

News / Korea / Taiwan ports may also return:

code	Meaning
517	Handshake API key missing
518	API key does not exist
519	No permission (news entitlement; Korea subscribe permission)
520	Korea/Taiwan: suffix does not match the market (.KS / .TW); news: this key already has a news connection
521	Handshake connection cap

A key without news access may also fail the /news HTTP handshake with 401.

Gateway / CDN

HTTP status	Meaning
401	Handshake auth failed
404	Path not found
429	Gateway rate limit
499	Client disconnect
524	Origin timeout