WebSocket 1009 Message Too Big vs 1015 TLS Handshake Failure
Both WebSocket 1009 (Message Too Big) and 1015 (TLS Handshake Failure) belong to the WebSocket Close Codes category. 1009 indicates that an endpoint is terminating the connection because it received a message that is too large for it to process. Meanwhile, 1015 means that a reserved value indicating the connection was closed because the TLS handshake failed. This code must not be set by an endpoint in a Close frame.
Description
An endpoint is terminating the connection because it received a message that is too large for it to process.
When You See It
The message payload exceeded the server's configured maximum frame or message size limit. Common when uploading large files or sending huge JSON payloads over WebSocket.
How to Fix
Reduce the message size by chunking large payloads into smaller frames. Alternatively, increase the server's max message size configuration if the large payload is expected.
Description
A reserved value indicating the connection was closed because the TLS handshake failed. This code must not be set by an endpoint in a Close frame.
When You See It
The wss:// (WebSocket Secure) connection failed during the TLS negotiation — commonly due to an expired certificate, untrusted CA, or TLS version mismatch.
How to Fix
Verify the server's TLS certificate is valid and not expired. Ensure both client and server support compatible TLS versions (TLS 1.2+). Check that intermediate certificates are properly chained.
Key Differences
WebSocket 1009: An endpoint is terminating the connection because it received a message that is too large for it to process.
WebSocket 1015: A reserved value indicating the connection was closed because the TLS handshake failed. This code must not be set by an endpoint in a Close frame.
You encounter 1009 when the message payload exceeded the server's configured maximum frame or message size limit. Common when uploading large files or sending huge JSON payloads over WebSocket.
You encounter 1015 when the wss:// (WebSocket Secure) connection failed during the TLS negotiation — commonly due to an expired certificate, untrusted CA, or TLS version mismatch.
When to Use Which
For 1009 (Message Too Big): Reduce the message size by chunking large payloads into smaller frames. Alternatively, increase the server's max message size configuration if the large payload is expected. For 1015 (TLS Handshake Failure): Verify the server's TLS certificate is valid and not expired. Ensure both client and server support compatible TLS versions (TLS 1.2+). Check that intermediate certificates are properly chained.