>  Hmm... i'd say it is impossible to obtain such results using FIrebird. See below
>
>  > C:\Program Files\Firebird\Firebird_2_5\bin>isql -user sysdba

-pass masterkey

> > Use CONNECT or CREATE DATABASE to specify a database
> > SQL> create database 'localhost:c:\temp\a.fdb';
>
> Note, there is no error, i.e. database is created and isql have active connection
>
> > SQL> show version;
> > ISQL Version: WI-V2.5.2.26540 Firebird 2.5
> > Server version
> > Cannot get server version without database connection

  I looked at ISQL's source code and found that such error message is be shown if
isc_version() call returns error. ISQL assume that error means no connection. But
there will be error also if server can't recognize info items passed by isc_version()
into underlying call of isc_database_info(). In Firebird 2.5 isc_version() implementation
passed isc_info_firebird_version tag into isc_database_info(). I'm almost sure you have
run *not Firebird 2.5* server and it have no knowledge about isc_info_firebird_version
and returns error.

 
Hope it is clear now.
Vlad

PS usage of isc_info_firebird_version (instead of isc_info_version) was introduced at year 2003,
so, i guess, you have tooo old Firebird running or even Interbase.