When installing the management tools for SQL Server 2008 R2 I received “SQL Server Setup has encountered the following error: “Unknown property.”
Looking on the web indicated that SQL Server Compact 3.5 could be causing the issue. Programs and Features showed SQL Server Compact 3.5 was installed, but I couldn’t uninstall, or repair the installation.
I downloaded the installation files here http://www.microsoft.com/en-us/download/details.aspx?id=5783 The installation instructions state that on a 64-bit computer you have to install the 32-bit and 64-bit versions of the files. Having installed both SSCERuntime_x86-ENU.msi and SSCERuntime_x64-ENU.msi I successfully re-ran the SQL Server 2008 R2 management tools installation. Both the 64-bit and 32-bit versions of SQL Server Compact are now listed in Programs and Features.
I’ve found that in some cases the Microsoft SQL Server Compact 3.5 SP2 x86 (SSCERuntime_x86-ENU.msi) installation can fail. In this case, open Registry Editor, navigate to HKEY_CLASSES_ROOT\Installer and search for the key relating to Microsoft SQL Server Compact 3.5 SP2 x86. Backup the key and delete it from the registry. The installation should now complete successfully.