Exception on Artifactory Import at Nexus 1.9

jvm 1    | 2011-01-18 09:11:36 INFO  [pool-1-thread-1] - org.sonatype.nexus.feeds.DefaultFeedRecorder - Importing Artifactory Backup. : Process started on Tue Jan 18 09:11:29 BRST 2011, finished on Tue Jan 18 09:11:36 BRST 2011 with error. Error message is: java.lang.NoClassDefFoundError, org/sonatype/nexus/tasks/ReindexTask Strack trace: java.lang.NoClassDefFoundError: org/sonatype/nexus/tasks/ReindexTask
jvm 1    |      at org.sonatype.nexus.plugin.migration.artifactory.DefaultArtifactoryMigrator.spawnAllMetadatas(DefaultArtifactoryMigrator.java:967)
jvm 1    |      at org.sonatype.nexus.plugin.migration.artifactory.DefaultArtifactoryMigrator.migrate(DefaultArtifactoryMigrator.java:269)
jvm 1    |      at org.sonatype.nexus.plugin.migration.artifactory.task.ArtifactoryMigrationTask.doRun(ArtifactoryMigrationTask.java:27)
jvm 1    |      at org.sonatype.nexus.scheduling.AbstractNexusTask.call(AbstractNexusTask.java:192)
jvm 1    |      at org.sonatype.scheduling.DefaultScheduledTask.call(DefaultScheduledTask.java:338)
jvm 1    |      at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
jvm 1    |      at java.util.concurrent.FutureTask.run(FutureTask.java:138)
jvm 1    |      at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98)
jvm 1    |      at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:207)
jvm 1    |      at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
jvm 1    |      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
jvm 1    |      at java.lang.Thread.run(Thread.java:619)
jvm 1    | Caused by: java.lang.ClassNotFoundException: org.sonatype.nexus.tasks.ReindexTask
jvm 1    |      at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
jvm 1    |      at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
jvm 1    |      at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:230)
jvm 1    |      ... 12 more
jvm 1    |
jvm 1    | java.lang.NoClassDefFoundError: org/sonatype/nexus/tasks/ReindexTask
jvm 1    |      at org.sonatype.nexus.plugin.migration.artifactory.DefaultArtifactoryMigrator.spawnAllMetadatas(DefaultArtifactoryMigrator.java:967)
jvm 1    |      at org.sonatype.nexus.plugin.migration.artifactory.DefaultArtifactoryMigrator.migrate(DefaultArtifactoryMigrator.java:269)
jvm 1    |      at org.sonatype.nexus.plugin.migration.artifactory.task.ArtifactoryMigrationTask.doRun(ArtifactoryMigrationTask.java:27)
jvm 1    |      at org.sonatype.nexus.scheduling.AbstractNexusTask.call(AbstractNexusTask.java:192)
jvm 1    |      at org.sonatype.scheduling.DefaultScheduledTask.call(DefaultScheduledTask.java:338)
jvm 1    |      at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
jvm 1    |      at java.util.concurrent.FutureTask.run(FutureTask.java:138)
jvm 1    |      at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:98)
jvm 1    |      at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:207)
jvm 1    |      at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
jvm 1    |      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
jvm 1    |      at java.lang.Thread.run(Thread.java:619)
jvm 1    | Caused by: java.lang.ClassNotFoundException: org.sonatype.nexus.tasks.ReindexTask
jvm 1    |      at org.codehaus.plexus.classworlds.strategy.SelfFirstStrategy.loadClass(SelfFirstStrategy.java:50)
jvm 1    |      at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:244)
jvm 1    |      at org.codehaus.plexus.classworlds.realm.ClassRealm.loadClass(ClassRealm.java:230)
jvm 1    |      ... 12 more
jvm 1    | 2011-01-18 09:11:40 INFO  [ool-1-thread-10] - org.sonatype.nexus.feeds.DefaultFeedRecorder - Updating repository index "codehaus" from path null and below. : Process started on Tue Jan 18 09:11:40 BRST 2011, not yet finished.