When I try to upgrade nexus2 to nexus3，nexus2 have 7 repositories ,the first repo is migrate successfully, but when I migrate the second repo，there is a failed in UI page , the failed is :Failed: java.lang.IllegalStateException: Content selector All_Maven2 is in use and cannot be deleted
Failed: java.lang.IllegalStateException: Content selector All_Maven2 is in use and cannot be deleted
so ,I can not continue next step , what should I do?