See http://forum.magnolia-cms.com/forum/thread.html?threadId=7b6ad7c4-e998-4999-ba17-02c577fa55f3&forumId=caf52257-62a1-40c4-8da7-cefb66785062

Migration script 1.2.1 throws exception when some metadata are missing:

2013-03-27 11:03:44,111 ERROR info.magnolia.module.InstallContextImpl : > Unable to migrate Site Main content for the following modulemybaloise-website
javax.jcr.PathNotFoundException: mgnl:template
at org.apache.jackrabbit.core.NodeImpl$11.perform(NodeImpl.java:2234)
at org.apache.jackrabbit.core.NodeImpl$11.perform(NodeImpl.java:2221)
at org.apache.jackrabbit.core.session.SessionState.perform(SessionState.java:216)
at org.apache.jackrabbit.core.ItemImpl.perform(ItemImpl.java:91)
at org.apache.jackrabbit.core.NodeImpl.getProperty(NodeImpl.java:2221)
at info.magnolia.jcr.wrapper.DelegateNodeWrapper.getProperty(DelegateNodeWrapper.java:244)
at info.magnolia.cms.core.MetaData.removeProperty(MetaData.java:439)
at info.magnolia.migration.task.content.UpdateWebsiteMainContentMigrationTask.transformFooter(UpdateWebsiteMainContentMigrationTask.java:184)
at info.magnolia.migration.task.content.UpdateWebsiteMainContentMigrationTask.transformContentOfPage(UpdateWebsiteMainContentMigrationTask.java:135)
at info.magnolia.migration.task.content.UpdateWebsiteMainContentMigrationTask.executeTask(UpdateWebsiteMainContentMigrationTask.java:99)
at info.magnolia.migration.task.AbstractMigrationTask.execute(AbstractMigrationTask.java:123)
at info.magnolia.migration.task.ContentModuleMigrationTask.executeStkBasedWebsiteMigrationTask(ContentModuleMigrationTask.java:130)
at info.magnolia.migration.task.ContentModuleMigrationTask.executeTask(ContentModuleMigrationTask.java:99)
at info.magnolia.migration.task.AbstractMigrationTask.execute(AbstractMigrationTask.java:123)
at info.magnolia.module.ModuleManagerImpl.applyDeltas(ModuleManagerImpl.java:499)
at info.magnolia.module.ModuleManagerImpl.installOrUpdateModule(ModuleManagerImpl.java:481)
at info.magnolia.module.ModuleManagerImpl$1.doExec(ModuleManagerImpl.java:270)
at info.magnolia.context.MgnlContext$VoidOp.exec(MgnlContext.java:443)
at info.magnolia.context.MgnlContext$VoidOp.exec(MgnlContext.java:440)
at info.magnolia.context.MgnlContext.doInSystemContext(MgnlContext.java:403)
at info.magnolia.module.ModuleManagerImpl.performInstallOrUpdate(ModuleManagerImpl.java:264)
at info.magnolia.module.ui.ModuleManagerWebUI$2.run(ModuleManagerWebUI.java:127)
at java.lang.Thread.run(Thread.java:619)