Migrating a Hudson instance

Quick post to hopefully help others with an error I got when moving our Hudson instance from Windows to its new home on a Linux server.

The basic migration is super easy - just zip up the Hudson home directory (default on Windows XP is C:\Documents and Settings\[username running Hudson]\.hudson) and restore it onto the new server. However, when you start your new Hudson instance you may see one of both of the following errors in the console output:

SEVERE: Timer task hudson.model.LoadStatistics$LoadStatisticsUpdater@74e8f8c5 failed
java.lang.AssertionError: class hudson.node_monitors.DiskSpaceMonitor is missing its descriptor
at hudson.model.Hudson.getDescriptorOrDie(Hudson.java:937)
at hudson.node_monitors.NodeMonitor.getDescriptor(NodeMonitor.java:83)
at hudson.node_monitors.NodeMonitor.getDescriptor(NodeMonitor.java:67)
at hudson.util.DescribableList.get(DescribableList.java:104)
at hudson.model.ComputerSet.(ComputerSet.java:356)
at hudson.model.LoadStatistics$LoadStatisticsUpdater.doRun(LoadStatistics.java:214)
at hudson.triggers.SafeTimerTask.run(SafeTimerTask.java:54)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)

Jul 29, 2010 1:47:39 PM hudson.triggers.SafeTimerTask run
SEVERE: Timer task hudson.model.LoadStatistics$LoadStatisticsUpdater@74e8f8c5 failed
java.lang.NoClassDefFoundError
at hudson.model.LoadStatistics$LoadStatisticsUpdater.doRun(LoadStatistics.java:214)
at hudson.triggers.SafeTimerTask.run(SafeTimerTask.java:54)
at java.util.TimerThread.mainLoop(Timer.java:512)
at java.util.TimerThread.run(Timer.java:462)

The fix is easy - just stop Hudson, delete the file nodeMonitors.xml in the main Hudson directory, and restart Hudson. It looks as if that file contains data that's specific to the old system; Hudson will recreate the file after restart.