I have a WebSocket server running on Undertow, and I get a lot of reports of people who can't connect to them, with any browser.

On the server logs, I see this error when they try to connect:

1ERROR CONNECTION -Jrr1g9eD79ojJNCanngxqhnxvkQfk5tMFPwiy_X
java.io.IOException: io.undertow.websockets.core.WebSocketFrameCorruptedException: UT002015: Extensions not allowed but received rsv of 4
at io.undertow.websockets.core.WebSocketChannel.parseFrame(WebSocketChannel.java:174)
at io.undertow.server.protocol.framed.AbstractFramedChannel.receive(AbstractFramedChannel.java:428)
at io.undertow.websockets.core.AbstractReceiveListener.handleEvent(AbstractReceiveListener.java:38)
at io.undertow.websockets.core.AbstractReceiveListener.handleEvent(AbstractReceiveListener.java:33)
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
at io.undertow.server.protocol.framed.AbstractFramedChannel$FrameReadListener.handleEvent(AbstractFramedChannel.java:932)
at io.undertow.server.protocol.framed.AbstractFramedChannel$FrameReadListener.handleEvent(AbstractFramedChannel.java:913)
at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
at org.xnio.conduits.ReadReadyHandler$ChannelListenerHandler.readReady(ReadReadyHandler.java:66)
at org.xnio.nio.NioSocketConduit.handleReady(NioSocketConduit.java:88)
at org.xnio.nio.WorkerThread.run(WorkerThread.java:559)
Caused by: io.undertow.websockets.core.WebSocketFrameCorruptedException: UT002015: Extensions not allowed but received rsv of 4
at io.undertow.websockets.core.protocol.version07.WebSocket07Channel$WebSocketFrameHeader.handle(WebSocket07Channel.java:255)
at io.undertow.websockets.core.WebSocketChannel.parseFrame(WebSocketChannel.java:164)
... 10 more
1CLOSE CONNECTION -Jrr1g9eD79ojJNCanngxqhnxvkQfk5tMFPwiy_X

It doesn't happen to most people, but it does happen very frequently, and therefore a lot of users can't use my application.

Is there anyway to make it ignore the RSV bit being set?