With the upcoming Microsoft Dynamics 365 Business Central Fall 2018 release, extensions V1 are no longer supported for on-premise installations.
While AppSource extensions have already been converted to extensions V2 , ISV extensions V1 must be converted to V2 before they can be installed on Business Central. Likewise, any customizations in Dynamics NAV 2016, Dynamics NAV 2017, or Dynamics NAV 2018 that are based on extensions V1 must be also converted to extensions V2 before upgrading to Business Central.