19 Jan 2014

Neo4j Backup: java.lang.ClassCastException: org.jboss.netty.buffer.BigEndianHeapChannelBuffer cannot be cast to org.neo4j.cluster.com.message.Message

(as Gabriel points out in the comments the ability to do a 'HA backup' doesn’t exist in more recent versions of Neo4j. I’ll leave this post here for people still running on older versions who encounter the error.)

When using Neo4j’s online backup facility there are two ways of triggering it, either by using the 'single://' or 'ha://' syntax and these behave slightly differently.

If you’re using the 'single://' syntax and don’t specify a port then it will connect to '6362' by default:

./neo4j-backup -from single://192.168.1.34 -to /mnt/backup/neo4j-backup

If you’ve changed the backup port via the 'online_backup_server' property in conf/neo4j.properties you’ll need to set the port explicitly:

online_backup_server=192.168.1.34:6363

./neo4j-backup -from single://192.168.1.34:6363 -to /mnt/backup/neo4j-backup

If you’re using the 'ha://' syntax then the backup client joins the HA cluster, works out which machine is the master and then creates a backup from that machine.

In order for the backup client to join the cluster it connects to port '5001' by default:

./neo4j-backup -from ha://192.168.1.34 -to /mnt/backup/neo4j-backup

If you’ve changed the 'ha.cluster_server' property then you’ll need to set the port explicitly:

ha.cluster_server=192.168.1.34:5002

./neo4j-backup -from ha://192.168.1.34:5002 -to /mnt/backup/neo4j-backup

A mistake that I made when first using this utility was to use the 'ha://' syntax with the backup port. e.g.

./neo4j-backup -from ha://192.168.1.34:6362 -to /mnt/backup/neo4j-backup

If you do this you’ll end up with the following exception:

2014-01-19 19:24:30.842+0000 ERROR [o.n.c.c.NetworkSender]: Receive exception:
java.lang.ClassCastException: org.jboss.netty.buffer.BigEndianHeapChannelBuffer cannot be cast to org.neo4j.cluster.com.message.Message
	at org.neo4j.cluster.com.NetworkSender$NetworkMessageSender.messageReceived(NetworkSender.java:409) ~[neo4j-cluster-2.0.0.jar:2.0.0]
	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:268) ~[netty-3.6.3.Final.jar:na]
	at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:255) ~[netty-3.6.3.Final.jar:na]
	at org.jboss.netty.channel.socket.nio.NioWorker.read(NioWorker.java:88) ~[netty-3.6.3.Final.jar:na]
	at org.jboss.netty.channel.socket.nio.AbstractNioWorker.process(AbstractNioWorker.java:107) ~[netty-3.6.3.Final.jar:na]
	at org.jboss.netty.channel.socket.nio.AbstractNioSelector.run(AbstractNioSelector.java:312) ~[netty-3.6.3.Final.jar:na]
	at org.jboss.netty.channel.socket.nio.AbstractNioWorker.run(AbstractNioWorker.java:88) ~[netty-3.6.3.Final.jar:na]
	at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:178) ~[netty-3.6.3.Final.jar:na]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [na:1.7.0_45]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [na:1.7.0_45]
	at java.lang.Thread.run(Thread.java:744) [na:1.7.0_45]

Let me know in the comments if any of this doesn’t make sense. There are lots of other examples to follow on neo4j-backup’s man page in the manual as well.

About the author

I'm currently working on short form content at ClickHouse. I publish short 5 minute videos showing how to solve data problems on YouTube @LearnDataWithMark. I previously worked on graph analytics at Neo4j, where I also co-authored the O'Reilly Graph Algorithms Book with Amy Hodler.