Can't format message nn:mmm -- message text not found
This means the firebird.msg file on the client is either not found or is a different version than the server.
This is due to the way error messages are reported by Firebird. When error happens, the server sends the error code to the client. Client then looks up into firebird.msg file on a local hard disk and retrieves the message text which is presented to the user. This enables multiple clients to have error messages in different languages (for example, four clients using the same Firebird server can have error messages in English, French, Spanish and German).
When new versions of Firebird are released, error messages might get added, changed or deleted. If you have a client which is different version than the server it connects to, you might get 'strange' error messages (error code changed), or a warning that message text is not found.
To fix this, make sure your client and server are the same version.
If you are manually setting up the client by copying Firebird files around, and you are getting this error message, try placing firebird.msg file in the parent directory of the one where fbclient.dll is located. (this suggestion was contributed by Fabio Gomes)