• Netty 5 Migration Guide
• Package
• Buffers
• Capacity
• Adaptors
• Changes in API
• Future / Promise
• ChannelFuture / ChannelPromise removal
• ProgressiveFuture / ProgressivePromise and ChannelProgressiveFuture / ChannelProgressivePromise removal
• VoidChannelPromise removal
• API changes to Promise and Future
• Channel
• Channel.eventLoop() renamed to Channel.executor()
• Return types changes from ChannelFuture to Future<Void>
• Half-closure
• ChannelHandlerContext doesn't extend AttributeMap anymore
• Channel.Unsafe removal
• ChannelOutboundBuffer not part of the Channel API anymore
• Channel.beforeBeforeWritable() removed and Channel.bytesBeforeUnwritable() renamed to writableBytes().
• ChannelPipeline
• ChannelPipeline.add*(EventExecutorGroup...) removed
• Return types changes from ChannelFuture to Future<Void>
• ChannelHandler
• Simplified handler type hierarchy
• channelRead0() → messageReceived()
• User events
• ChannelHandler.pendingOutboundBytes(...) method added
• EventLoopGroup / EventLoop
• EventLoopGroup.isCompatible(...) method added
• EventLoop.registerForIo(...) and EventLoop.deregisterForIo added
• Rarely used codecs moved to Netty Contrib