XHTML migration dies on java.io.IOException: The character '^K' is an invalid XML character

2011-09-21 13:18:13,123 ERROR [http-8090-3] [admin.actions.upgrade.ForceUpgradeAction] doInTransactionWithoutResult Upgrade failed with exception: java.util.concurrent.ExecutionException: java.lang.RuntimeException: org.owasp.validator.html.ScanException: java.io.IOException: The character '^K' is an invalid XML character
 -- referer: http://localhost:8090/admin/do-force-upgrade.action?atl_token=b867c36fd0d30b43f1f3a79338556e13ce5f4eac&upgradeTaskToRun=wikiToXhtmlMigrationUpgradeTask&confirm=Force+Upgrade | url: /admin/do-force-upgrade.action | userName: admin | action: do-force-upgrade
com.atlassian.confluence.content.render.xhtml.migration.exceptions.MigrationException: java.util.concurrent.ExecutionException: java.lang.RuntimeException: org.owasp.validator.html.ScanException: java.io.IOException: The character '^K' is an invalid XML character
        at com.atlassian.confluence.content.render.xhtml.migration.DefaultWikiToXhtmlSiteMigrator.migrateSite(DefaultWikiToXhtmlSiteMigrator.java:164)
        at com.atlassian.confluence.upgrade.upgradetask.WikiToXhtmlMigrationUpgradeTask.doDeferredUpgrade(WikiToXhtmlMigrationUpgradeTask.java:40)
        at com.atlassian.confluence.admin.actions.upgrade.ForceUpgradeAction$1.doInTransactionWithoutResult(ForceUpgradeAction.java:85)
        at org.springframework.transaction.support.TransactionCallbackWithoutResult.doInTransaction(TransactionCallbackWithoutResult.java:33)
        at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:128)
        at com.atlassian.confluence.admin.actions.upgrade.ForceUpgradeAction.execute(ForceUpgradeAction.java:103)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:168)
        at com.opensymphony.xwork.interceptor.AroundInterceptor.intercept(AroundInterceptor.java:35)
        at com.opensymphony.xwork.DefaultActionInvocation.invoke(DefaultActionInvocation.java:165)