2010-07-01 13:35:57,461 main FATAL [crowd.console.listener.UpgradeListener] Failed to initialise Crowd container
java.lang.IllegalArgumentException: argument credential cannot be null
at org.apache.commons.lang.Validate.notNull(Validate.java:203)
at com.atlassian.crowd.integration.model.user.UserTemplateWithCredentialAndAttributes.<init>(UserTemplateWithCredentialAndAttributes.java:25)
at com.atlassian.crowd.migration.legacy.database.UserMapper.importUsersFromDatabase(UserMapper.java:108)
at com.atlassian.crowd.migration.legacy.database.UserMapper.importFromDatabase(UserMapper.java:44)
at com.atlassian.crowd.migration.legacy.database.DatabaseMigrator.importDatabase(DatabaseMigrator.java:38)
at com.atlassian.crowd.migration.legacy.database.DatabaseMigrator$$FastClassByCGLIB$$20c39eb4.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:700)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.orm.hibernate3.HibernateInterceptor.invoke(HibernateInterceptor.java:111)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:635)
at com.atlassian.crowd.migration.legacy.database.DatabaseMigrator$$EnhancerByCGLIB$$90b763d6.importDatabase(<generated>)
at com.atlassian.crowd.migration.legacy.database.DatabaseMigrationManager.doDatabaseMigration(DatabaseMigrationManager.java:41)
at com.atlassian.crowd.console.listener.UpgradeListener.migrateAndUpgradeCrowd(UpgradeListener.java:120)
at com.atlassian.crowd.console.listener.UpgradeListener.contextInitialized(UpgradeListener.java:47)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3934)
Bug
High
Justin Koke
added a comment - Committed to both branch and trunk. 
For the search engines:
You'll see this error in the logs if you are encountering this bug.
2010-07-01 13:35:57,461 main FATAL [crowd.console.listener.UpgradeListener] Failed to initialise Crowd container java.lang.IllegalArgumentException: argument credential cannot be null at org.apache.commons.lang.Validate.notNull(Validate.java:203) at com.atlassian.crowd.integration.model.user.UserTemplateWithCredentialAndAttributes.<init>(UserTemplateWithCredentialAndAttributes.java:25) at com.atlassian.crowd.migration.legacy.database.UserMapper.importUsersFromDatabase(UserMapper.java:108) at com.atlassian.crowd.migration.legacy.database.UserMapper.importFromDatabase(UserMapper.java:44) at com.atlassian.crowd.migration.legacy.database.DatabaseMigrator.importDatabase(DatabaseMigrator.java:38) at com.atlassian.crowd.migration.legacy.database.DatabaseMigrator$$FastClassByCGLIB$$20c39eb4.invoke(<generated>) at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149) at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:700) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:149) at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:106) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.orm.hibernate3.HibernateInterceptor.invoke(HibernateInterceptor.java:111) at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:635) at com.atlassian.crowd.migration.legacy.database.DatabaseMigrator$$EnhancerByCGLIB$$90b763d6.importDatabase(<generated>) at com.atlassian.crowd.migration.legacy.database.DatabaseMigrationManager.doDatabaseMigration(DatabaseMigrationManager.java:41) at com.atlassian.crowd.console.listener.UpgradeListener.migrateAndUpgradeCrowd(UpgradeListener.java:120) at com.atlassian.crowd.console.listener.UpgradeListener.contextInitialized(UpgradeListener.java:47) at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3934)