C:\Firebird-2.1.5.18497-0_Win32\bin>gbak -v -user SYSDBA -password masterkey c:\db.fdb c:\db.fbk
gbak: ERROR:file C:\DB.FDB is not a valid database
gbak:Exiting before completion due to errors

C:\Firebird-2.1.5.18497-0_Win32\bin>isql
Use CONNECT or CREATE DATABASE to specify a database
SQL> CONNECT 'localhost:c:/DB.fdb' user 'SYSDBA' password 'masterkey';
Statement failed, SQLCODE = -922
file C:\DB.FDB is not a valid database
SQL>

Attempting to connect to:
C:\DB.FDB
 
Connecting... Failed!
------------------------------------
Connection authorization failure.
file C:\DB.FDB is not a valid database.
 
Attempting to connect to services manager... Failed!
------------------------------------

Unsuccessful execution caused by an unavailable resource.
Cannot attach to services manager.
user name and password are required while attaching to the services manager.

C:\Firebird-2.1.5.18497-0_Win32\bin>gstat.exe -h db.fdb
Wrong ODS version, expected 11, encountered 22805