This database file is not compatible with the current instance of SQL Server.

I downloaded some project from here, this included some test MS SQL Server database file called 'SchoolDB.mdf'. When I try to open it in Visual Studio 2019, VS throws error as -

To resolve this issue, you must upgrade the database file by creating a new data connection, or you must modify the existing connection to this database file.

For more information, see https://go.microsoft.com/fwlink/?LinkId=235986

Found solution here