The newest Skype for Business 2015 update (Version 9319.534) from 7/31/2018 supports SQL Server 2016 with SP1 now. If you are using SQL Server 2008 R2 as a Back End database, you should not apply this update. For more information, see KB4345985 “Failed to setup database rtcxds” error when you upgrade the SQL Server 2008 R2 back-end database in Skype for Business Server 2015. Please Download the Update an follow these installation instructions.Read More →