I do not know how to reproduce it
>>> Caused by: java.lang.IllegalArgumentException: launchSearchAtStartup cannot be null with a ResultDisplayType not equals to ON_PAGE
at org.ametys.web.frontoffice.search.instance.model.ResultDisplay.<init>(ResultDisplay.java:67)
at org.ametys.web.frontoffice.search.instance.SearchServiceInstanceFactory._createResultDisplay(SearchServiceInstanceFactory.java:373)
at org.ametys.web.frontoffice.search.instance.SearchServiceInstanceFactory.createSearchServiceInstance(SearchServiceInstanceFactory.java:142)
at org.ametys.web.frontoffice.search.instance.SearchServiceInstanceManager.get(SearchServiceInstanceManager.java:97)
at org.ametys.web.frontoffice.search.SearchService.isCacheable(SearchService.java:167)
at org.ametys.web.repository.PageGenerator._saxZoneItem(PageGenerator.java:450)