During the Adobe Connect Server installation process, the installer detects either an existing version or incomplete uninstall of Microsoft SQL Server. This issue occurs when you install the Microsoft Desktop Engine (MSDE) included with Adobe Connect Server and also with Microsoft SQL server.
If you install a Microsoft SQL server, Adobe recommends that it is installed on a different computer than the Adobe Connect Server.
(Optional) If SQL Server or MSDE is uninstalled, your system can still encounter this issue. To uninstall Microsoft SQL Server or MSDE, Adobe recommends that you see the applicable Microsoft knowledgebase articles here.