Starting with Firebird 2.5, Firebird Embedded on Windows behaves like the SuperClassic server model, which means it uses shared access to the database files, and that the same database can be accessed by multiple Firebird Embedded applications and Firebird servers in the Classic or SuperClassic server model (but not SuperServer) if they are running on the same machine. The downside of this change is that embedded applications need to be able to create, read and write the shared database lockfiles (in C:\ProgramData\Firebird).