I get the following error after/in the step "Sicherung":

Sie haben einen Fehler in Ihrer lokalen Installation von LimeSurvey. Siehe:
{"success":false,"message":"Weder Update noch zugeh\u00f6rige Behavior haben einen Scope \"_renderErrorString\".","error":{"code":500,"type":"CException","errorCode":0,"message":"Weder Update noch zugeh\u00f6rige Behavior haben einen Scope \"_renderErrorString\".","file":"E:\WWW\UMFRAGE\framework\base\CComponent.php","line":266,"trace":"#0 E:\WWW\UMFRAGE\application\controllers\admin\update.php(405): CComponent->__call('_renderErrorStr...', Array)\n#1 [internal function]: Update->step4()\n#2 E:\WWW\UMFRAGE\framework\web\actions\CAction.php(115): ReflectionMethod->invokeArgs(Object(Update), Array)\n#3 E:\WWW\UMFRAGE\application\core\SurveyCommonAction.php(83): CAction->runWithParamsInternal(Object(Update), Object(ReflectionMethod), Array)\n#4 E:\WWW\UMFRAGE\framework\web\CController.php(308): SurveyCommonAction->runWithParams(Array)\n#5 E:\WWW\UMFRAGE\framework\web\CController.php(286): CController->runAction(Object(Update))\n#6 E:\WWW\UMFRAGE\framework\web\CController.php(265): CController->runActionWithFilters(Object(Update), Array)\n#7 E:\WWW\UMFRAGE\application\controllers\AdminController.php(202): CController->run('update')\n#8 E:\WWW\UMFRAGE\framework\web\CWebApplication.php(282): AdminController->run('update')\n#9 E:\WWW\UMFRAGE\framework\web\CWebApplication.php(141): CWebApplication->runController('admin\/update\/sa...')\n#10 E:\WWW\UMFRAGE\framework\base\CApplication.php(185): CWebApplication->processRequest()\n#11 E:\WWW\UMFRAGE\index.php(192): CApplication->run()\n#12 {main}","traces":[{"file":"E:\WWW\UMFRAGE\application\controllers\admin\update.php","line":405,"function":"__call","class":"CComponent","type":"->","args":["_renderErrorString",["cant_remove_deleted_files"]]},{"function":"step4","class":"Update","type":"->","args":[],"file":"unknown","line":0},{"file":"E:\WWW\UMFRAGE\framework\web\actions\CAction.php","line":115,"function":"invokeArgs","class":"ReflectionMethod","type":"->","args":[{},[]]},{"file":"E:\WWW\UMFRAGE\application\core\SurveyCommonAction.php","line":83,"function":"runWithParamsInternal","class":"CAction","type":"->","args":[{},{"name":"step4","class":"Update"},{"r":"admin\/update\/sa\/step4","sa":"step4"}]},{"file":"E:\WWW\UMFRAGE\framework\web\CController.php","line":308,"function":"runWithParams","class":"SurveyCommonAction","type":"->","args":[{"r":"admin\/update\/sa\/step4","sa":"step4"}]},{"file":"E:\WWW\UMFRAGE\framework\web\CController.php","line":286,"function":"runAction","class":"CController","type":"->","args":[{}]},{"file":"E:\WWW\UMFRAGE\framework\web\CController.php","line":265,"function":"runActionWithFilters","class":"CController","type":"->","args":[{},[]]},{"file":"E:\WWW\UMFRAGE\application\controllers\AdminController.php","line":202,"function":"run","class":"CController","type":"->","args":["update"]},{"file":"E:\WWW\UMFRAGE\framework\web\CWebApplication.php","line":282,"function":"run","class":"AdminController","type":"->","args":["update"]},{"file":"E:\WWW\UMFRAGE\framework\web\CWebApplication.php","line":141,"function":"runController","class":"CWebApplication","type":"->","args":["admin\/update\/sa\/step4"]},{"file":"E:\WWW\UMFRAGE\framework\base\CApplication.php","line":185,"function":"processRequest","class":"CWebApplication","type":"->","args":[]},{"file":"E:\WWW\UMFRAGE\index.php","line":192,"function":"run","class":"CApplication","type":"->","args":[]}]}}