Commented by: @pavel-zotov

PS. When connect to empty (new) .fdb via TCP rather than local:

[firebird@firebirdG Zotov]$ isql localhost:/u01/db/firebird/Zotov/td1.fdb
Database: localhost:/u01/db/firebird/Zotov/td1.fdb
SQL> recreate global temporary table ttt$t1(id int);
SQL> commit;
SQL> recreate global temporary table ttt$t1 (
CON> id int primary key
CON> ,ref_id int
CON> ,constraint ttt$fk foreign key (ref_id) references ttt$t1(id)
CON> );
Statement failed, SQLSTATE = 08006
Error reading data from the connection.

-- no coredump at this case.

firebird.log:
----------------
firebirdG Sat Apr 28 00:40:04 2012
REMOTE INTERFACE/gds__detach: Unsuccesful detach from database.
Uncommitted work may have been lost

Commented by: @pavel-zotov

On Windows (both local and TCP):

C:\MIX\firebird\fb25>isql localhost/3050:C:\MIX\firebird\fb25\TWW.FDB
Database: localhost/3050:C:\MIX\firebird\fb25\TWW.FDB
SQL> show version;
ISQL Version: WI-V2.5.1.26351 Firebird 2.5
Server version:
Firebird/x86/Windows NT (access method), version "WI-V2.5.1.26351 Firebird 2.5"
Firebird/x86/Windows NT (remote server), version "WI-V2.5.1.26351 Firebird 2.5/tcp (csprog)/P12"
Firebird/x86/Windows NT (remote interface), version "WI-V2.5.1.26351 Firebird 2.5/tcp (csprog)/P12"
on disk structure version 11.2

SQL> in r; -- script see above
Statement failed, SQLSTATE = 08001
I/O error during "ReadFile" operation for file "C:\MIX\FIREBIRD\FB25\TWW.FDB"
-Error while trying to read from file
-Wrong descriptor
After line 2 in file r
SQL> quit;