When you run Microsoft Skype for Business Server 2015 Deployment Wizard to install Local Configuration Store on a computer that has Unified Communications Managed API (UCMA) 5.0 SDK installed, the installer cannot find the location of Microsoft Skype for Business Server 2015, Core Components (OCSCore.msi). You receive the following error message:
INSTALLDIR="C:\Program Files\Skype for Business Server 2015\")...failure code 1638
Error returned while installing OcsCore.msi(Feature_LocalMgmtStore), code 1638. Error Message: Another version of this product is already installed. Installation of this version cannot continue. To configure or remove the existing version of this product, use Add/Remove Programs in Control Panel. For more details please consult log at C:\Users\[User]\AppData\Local\Temp\1\Add-OcsCore.msi-Feature_LocalMgmtStore-[Date][Time].log