We are pleased to announce that Lucity 2016r2 SP1 (Jan 2017) and Lucity 2017 (Feb 2017) will include built-in support for the latest Esri® ArcGIS 10.5 release! 10.5 is not your typical maintenance and quality improvement release. There are some major changes included in 10.5 especially to ArcGIS for Server and named user levels. Earlier versions of Lucity that fall under active maintenance can be upgraded to 10.5, but may require some additional steps as outlined in this knowledge base article.
Feel free to contact a Lucity support representative for more details, or refer to the Lucity Support Center for updates to our ArcGIS version support.