This code worked fine in 1.0.1. I posted earlier today about getting strange exceptions after upgrading to 1.0.2, and it appears that GORM is having trouble with my base class. I rebuilt the project from scratch in a brand new 1.0.2 application to eliminate possibility of a bad upgrade. I am building a run-time test environment, and my model is that I have run-time tests that are run by test plans. Test plans can be made up of sub-plans, to an arbitrary level. (Plans can be part of many plans too, but I haven't started on making that a many-2-many mapping yet). I also use the same composite pattern adopted by JUnit, a la test suites, so both plans and tests are 'runnable' and inherit from a base class. Also, any AbstractTestRunnable can have a TestRun history, most notably recording what ran, who ran it and the result. TestRuns also are associated, in that I may want to issue a report of the results of all tests for a particular Plan. The hierarchy is attached to the end if this description. In my bootstrap, I have this: def plan = new Plan(name: 'First Plan', timeToRun: new Date(108, 3, 1)) def rtt = new RuntimeTest(name: "Hard Kill of TS1", scriptFile: "TSMDBHardKill") plan.addToRunnables rtt In 1.0.1 this worked great. In 1.0.2 I get an exception on the last line above: 2008-03-30 11:40:23.283::WARN: Failed startup of context org.mortbay.jetty.webapp.WebAppContext@c0d2d3{/BidsRTTE,c:\java\BidsRTTE/web-app} org.codehaus.groovy.runtime.InvokerInvocationException: org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'First Plan' with class 'Plan' to class 'java.util.Set' at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:92) at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:226) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:899) at groovy.lang.ExpandoMetaClass.invokeMethod(ExpandoMetaClass.java:946) at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:740) at groovy.lang.Closure.call(Closure.java:292) at org.codehaus.groovy.grails.commons.DefaultGrailsBootstrapClass.callInit(DefaultGrailsBootstrapClass.java:43) at org.codehaus.groovy.grails.web.context.GrailsConfigUtils.executeGrailsBootstraps(GrailsConfigUtils.java:64) at org.codehaus.groovy.grails.web.context.GrailsContextLoader.createWebApplicationContext(GrailsContextLoader.java:51) Here as promised is my Domain. class AbstractTestRunnable { static hasMany = [ testRuns: TestRun, runnables: AbstractTestRunnable, runners: AbstractTestRunnable ] static mappedBy = [ testRuns: 'runner' ] String name List testRuns } class RuntimeTest extends AbstractTestRunnable { String scriptFile } class Plan extends AbstractTestRunnable{ Date timeToRun } class TestRun { static hasMany = [children: TestRun] static belongsTo = TestRun AbstractTestRunnable runnable AbstractTestRunnable runner List children Date started Date completed boolean successful String exception static constraints = { exception(nullable: true) runnable(nullable: true) }