You have an error inside your local installation of LimeSurvey. See:
{"success":false,"message":"Alias \"ext.AlertWidget.AlertWidget\" is invalid. Make sure it points to an existing PHP file and the file is readable.","error":{"code":500,"type":"CException","errorCode":0,"message":"Alias \"ext.AlertWidget.AlertWidget\" is invalid. Make sure it points to an existing PHP file and the file is readable.","file":"\/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/YiiBase.php","line":330,"trace":"#0 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CWidgetFactory.php(146): YiiBase::import()\n#1 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CBaseController.php(146): CWidgetFactory->createWidget()\n#2 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CBaseController.php(181): CBaseController->createWidget()\n#3 \/var\/www\/clients\/client213\/web2772\/web\/application\/views\/admin\/update\/updater\/steps\/_final.php(19): CBaseController->widget()\n#4 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CBaseController.php(126): require('...')\n#5 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CBaseController.php(95): CBaseController->renderInternal()\n#6 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CController.php(872): CBaseController->renderFile()\n#7 \/var\/www\/clients\/client213\/web2772\/web\/application\/controllers\/AdminController.php(261): CController->renderPartial()\n#8 \/var\/www\/clients\/client213\/web2772\/web\/application\/controllers\/admin\/Update.php(436): AdminController->renderPartial()\n#9 [internal function]: Update->step4()\n#10 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/actions\/CAction.php(115): ReflectionMethod->invokeArgs()\n#11 \/var\/www\/clients\/client213\/web2772\/web\/application\/core\/SurveyCommonAction.php(83): CAction->runWithParamsInternal()\n#12 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CController.php(308): SurveyCommonAction->runWithParams()\n#13 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CController.php(286): CController->runAction()\n#14 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CController.php(265): CController->runActionWithFilters()\n#15 \/var\/www\/clients\/client213\/web2772\/web\/application\/controllers\/AdminController.php(202): CController->run()\n#16 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CWebApplication.php(282): AdminController->run()\n#17 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/web\/CWebApplication.php(141): CWebApplication->runController()\n#18 \/var\/www\/clients\/client213\/web2772\/web\/vendor\/yiisoft\/yii\/framework\/base\/CApplication.php(185): CWebApplication->processRequest()\n#19 \/var\/www\/clients\/client213\/web2772\/web\/index.php(161): CApplication->run()\n#20 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