Saw this in the RC1-3 candidate (after start_mininet.sh on both nodes, using just our feature and restconf):

2014-09-18 23:41:42,158 | ERROR | ntLoopGroup-10-2 | SessionManagerOFImpl | 212 - org.opendaylight.openflowplugin - 0.0.3.Helium-RC1-3-v201409190324 | Unhandled exeption occured while invoking onSessionRemoved on listener
java.lang.NullPointerException
at org.opendaylight.openflowplugin.openflow.md.core.sal.SalRegistrationManager.onSessionRemoved(SalRegistrationManager.java:116)[212:org.opendaylight.openflowplugin:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowplugin.openflow.md.core.session.SessionManagerOFImpl$1.onSessionRemoved(SessionManagerOFImpl.java:204)[212:org.opendaylight.openflowplugin:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowplugin.openflow.md.core.session.SessionManagerOFImpl.removeSessionContext(SessionManagerOFImpl.java:127)[212:org.opendaylight.openflowplugin:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowplugin.openflow.md.core.session.SessionManagerOFImpl.invalidateDeadSessionContext(SessionManagerOFImpl.java:117)[212:org.opendaylight.openflowplugin:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowplugin.openflow.md.core.session.SessionManagerOFImpl.invalidateOnDisconnect(SessionManagerOFImpl.java:169)[212:org.opendaylight.openflowplugin:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowplugin.openflow.md.core.ConnectionConductorImpl.onDisconnectEvent(ConnectionConductorImpl.java:358)[212:org.opendaylight.openflowplugin:0.0.3.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowjava.protocol.impl.connection.ConnectionAdapterImpl.consume(ConnectionAdapterImpl.java:275)[210:org.opendaylight.openflowjava.openflow-protocol-impl:0.5.0.Helium-RC1-3-v201409190324]
at org.opendaylight.openflowjava.protocol.impl.core.DelegatingInboundHandler.channelInactive(DelegatingInboundHandler.java:55)[210:org.opendaylight.openflowjava.openflow-protocol-impl:0.5.0.Helium-RC1-3-v201409190324]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:228)[149:io.netty.codec:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(ByteToMessageDecoder.java:228)[149:io.netty.codec:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75)[128:io.netty.transport:4.0.23.Final]
at io.netty.handler.timeout.ReadTimeoutHandler.channelInactive(ReadTimeoutHandler.java:144)[150:io.netty.handler:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.ChannelInboundHandlerAdapter.channelInactive(ChannelInboundHandlerAdapter.java:75)[128:io.netty.transport:4.0.23.Final]
at org.opendaylight.openflowjava.protocol.impl.connection.ChannelOutboundQueue.channelInactive(ChannelOutboundQueue.java:257)[210:org.opendaylight.openflowjava.openflow-protocol-impl:0.5.0.Helium-RC1-3-v201409190324]
at io.netty.channel.AbstractChannelHandlerContext.invokeChannelInactive(AbstractChannelHandlerContext.java:233)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannelHandlerContext.fireChannelInactive(AbstractChannelHandlerContext.java:219)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.DefaultChannelPipeline.fireChannelInactive(DefaultChannelPipeline.java:769)[128:io.netty.transport:4.0.23.Final]
at io.netty.channel.AbstractChannel$AbstractUnsafe$5.run(AbstractChannel.java:567)[128:io.netty.transport:4.0.23.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:351)[129:io.netty.common:4.0.23.Final]
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:350)[128:io.netty.transport:4.0.23.Final]
at io.netty.util.concurrent.SingleThreadEventExecutor$2.run(SingleThreadEventExecutor.java:116)[129:io.netty.common:4.0.23.Final]
at io.netty.util.concurrent.DefaultThreadFactory$DefaultRunnableDecorator.run(DefaultThreadFactory.java:137)[129:io.netty.common:4.0.23.Final]
at java.lang.Thread.run(Thread.java:745)[:1.7.0_65]