This error appears when launching or running a WinCC (TIA Portal / WinCC Professional) 7.5 runtime or project and the runtime fails to initialize. Causes include licensing/activation issues, corrupted project files or graphics, missing or incompatible runtime components, permission problems, or environment mismatches (OS, .NET, Visual C++ runtimes).
WinCC 7.5 uses specific versions of SQL Server (e.g., SQL Server 2014 or 2017 Standard/Express). If the SQL instance WINCC is stopped, disabled, or corrupted, WinCC cannot start its basic data applications. A Basic Application Could Not Be Started Wincc 7.5
This single action resolves the majority of cases. A Basic Application Could Not Be Started — WinCC 7
If the new project opens without the error, your original project is the problem. Microsoft SQL Server Issues WinCC 7