> I am using Firebird embedded 3.0.1.

> I receive an EDatabase error : "[ODBC Firebird Driver]Database is
> probably already opened by another engine instance on another Windows session."

> when trying to connect to a firebird db simultaneously in
> Adminstrator (elevated) mode and non-elevated mode with the same user account.

It is not a question of "elevated" vs "non-elevated" users. Embedded
is *by design* a single-user model. A successful embedded connection
locks out all other users from connecting to the same database - hence
the error message you see. The *same user* can make multiple
connections from within the same application space.

> Does anyone know how to solve this issue?

It depends on the issue you are trying to solve. But if you want
multi-user access then you need to install a server. If you want
multiple embedded connections to connect concurrently, configure the
server as Classic or Superclassic. Note that the default server
installation is Superserver, which also cannot share with embedded
connections.

Describe what you want to achieve in real life and someone will advise
you about the best model for your requirements.

Incidentally, since you are using Delphi, be aware that embedded is a
deployment model, not a development one. You can't have an embedded
connection in the IDE space and another one in the executable space.
So you need to have a server running for your Delphi development, even
if you intend to deploy an embedded app for single-user use.

Helen