Exceptions and errors

In addition to the 40x and 50x headers, error responses come with the name of the exception generated internally by the API server.

HTTP/1.1 500 Server error
Content-Type: application/json

{
    "status": "error",
    "message": "Error message",
    "error_type": "GeneralException"
}

Error types

Exception	HTTP	Description
AuthenticationError	401	Login failed — invalid credentials or token expired
TokenException	403	Session expired or invalidated. Must re-login
RequestError	400–500	General request failure with status code and message
InputException	400	Missing required fields, bad parameter values
OrderException	400	Order-related failures (placement, fetch, etc.)
MarginException	400	Insufficient funds for order placement
PositionException	400	Position-related errors
NetworkException	502	Unable to communicate with the OMS
DataException	500	Internal system error parsing OMS response
GeneralException	500	Unclassified error

Common HTTP error codes

Code	Meaning
400	Missing or bad request parameters or values
401	Authentication failed
403	Session expired or invalidated. Must re-login
404	Requested resource not found
405	Request method not allowed on the endpoint
429	Too many requests (rate limiting)
500	Unexpected server error
502	Backend OMS is down
503	Service unavailable
504	Gateway timeout

SDK error handling

PythonC#

SDK methods raise on failure rather than returning error dicts:

Exception	Raised when
AuthenticationError	Login fails — transport error, non-200, or status != "success"
RequestError (status_code property)	Any non-(200, 201) API response, connection failure (0), or timeout (0). One automatic re-login + retry is attempted on 401 first
ValueError	Invalid local input — unknown instrument symbol, malformed EXCHANGE\|NAME string
RuntimeError	Instrument master download returns a non-200 status

All SDK exceptions derive from BlitzSDKException (from blitzsdk.common.exceptions import ...).

All failures throw BlitzConnectException:

Property	Meaning
HttpStatusCode	HTTP status code; 0 for transport-level failures (retries exhausted) and deserialization errors
RawResponseBody	Raw server body attached when available
ApiError	Best-effort parsed BlitzApiResponse<object> of the error body

WebSocket clients never throw for runtime issues — they surface problems via OnError events instead.