The DB file is created by Firebird server last version. How we can solve this problem?
Don't listen to Thaddy. It's his personal opinion.
I've worked with Firebird for over 18 years (since version 1.5 and Interbase before that) and love it and have absolutely no problems with it.
The problem from you starting post is that you have an existing DB made in Firebird 3 and you want to access it using Firebird 2.5.
That's not possible.
Install Firebird 3.0 or use a database which is for 2.5.
Where does this database come from?
BTW. Lazarus can do Firebird 3.0 perfectly fine.
What components are your using.
You could think about using IBX for Lazarus (special for Firebird).
But I'm sure the default components can handle it too (because the drivers haven't changed).
But you can't access a 3.0 database with Firebird 2.5. That's a problem with any database you will use.