Trying to understand what is wrong with WebSocket communication since the fact application is trying resend message.

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The last WebSocket packet contains error:

The client frame set the reserved bits to [4] for a message with opCode [7] which was not supported by this endpoint

WebSocket server runs on Tomcat 9.


The client is sending a frame with OpCode 7. That OpCode is not defined by RFC 6455 and does not appear in the IANA registry so Tomcat does not know how to handle it and therefore closes the connection.

This looks like a broken client to me.

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