WebSocket 1003 Unsupported Data vs 1011 Internal Error
Both WebSocket 1003 (Unsupported Data) and 1011 (Internal Error) belong to the WebSocket Close Codes category. 1003 indicates that an endpoint received a type of data it cannot accept. For example, a text-only endpoint received a binary message, or vice versa. Meanwhile, 1011 means that the server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request.
Description
An endpoint received a type of data it cannot accept. For example, a text-only endpoint received a binary message, or vice versa.
When You See It
The client sent a binary frame to a server that only handles text, or a text frame to a binary-only endpoint. The receiver does not know how to process this data type.
How to Fix
Verify the message type (text vs binary) matches what the server expects. Update your client to send the correct opcode for the data format.
Description
The server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request.
When You See It
The server hit an unhandled exception or crashed while processing a WebSocket message. This is the WebSocket equivalent of HTTP 500 Internal Server Error.
How to Fix
Check the server-side application logs for stack traces and exceptions. Fix the underlying bug that caused the crash and add proper error handling around message processing.
Key Differences
WebSocket 1003: An endpoint received a type of data it cannot accept. For example, a text-only endpoint received a binary message, or vice versa.
WebSocket 1011: The server is terminating the connection because it encountered an unexpected condition that prevented it from fulfilling the request.
You encounter 1003 when the client sent a binary frame to a server that only handles text, or a text frame to a binary-only endpoint. The receiver does not know how to process this data type.
You encounter 1011 when the server hit an unhandled exception or crashed while processing a WebSocket message. This is the WebSocket equivalent of HTTP 500 Internal Server Error.
When to Use Which
For 1003 (Unsupported Data): Verify the message type (text vs binary) matches what the server expects. Update your client to send the correct opcode for the data format. For 1011 (Internal Error): Check the server-side application logs for stack traces and exceptions. Fix the underlying bug that caused the crash and add proper error handling around message processing.