description: Create following script:

shell del C:\MIX\firebird\QA\fbt-repo\tmp\c2284.fdb 2>nul;
create database 'localhost:C:\MIX\firebird\QA\fbt-repo\tmp\c2284.fdb' user 'SYSDBA' password 'masterkey';

recreate table test_cs__detail(x int);
recreate table test_cs__master(x int);
commit;

set autoddl off;
recreate table test_cs__master (
str_pk varchar(32) character set UTF8 not null, --------------------- [ 1 ]
primary key (str_pk) using index test_s_master_pk
);

recreate table test_cs__detail (
str_pk varchar(32) character set WIN1251 not null, ------------------ [ 2 ]
foreign key (str_pk) references test_cs__master (str_pk)
);

set echo on;

commit;
rollback;

Console output:

ISQL Version: WI-V3.0.3.32854 Firebird 3.0
Server version:
WI-V3.0.3.32854 Firebird 3.0
WI-V3.0.3.32854 Firebird 3.0/tcp (csprog)/P15:C
WI-V3.0.3.32854 Firebird 3.0/tcp (csprog)/P15:C

commit;
Statement failed, SQLSTATE = 08001
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
-Error while trying to write to file
-invalid descriptor // in national codepage
After line 19 in file crash-on-pk-fk-with-diff-cset.sql
rollback;
Statement failed, SQLSTATE = XX000
internal Firebird consistency check (can't continue after bugcheck)
After line 21 in file crash-on-pk-fk-with-diff-cset.sql
Statement failed, SQLSTATE = XX000
internal Firebird consistency check (can't continue after bugcheck)
After line 21 in file crash-on-pk-fk-with-diff-cset.sql

Note:
1. Both tables have to be created BEFORE 'recreate table' statement, i.e. they must already exist;
2. Charsets in PK and FK fields differ.

PS.

I thought that this bug is related to CORE5677 or CORE2284, but after discussion with Vlal it was decided to create new ticket.
The same result on WI-V2.5.8.27083 and WI-T4.0.0.832 -- i.e. this bug is old enough.

firebird.log

CSPROG Thu Dec 14 20:49:31 2017
Database: C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB
internal Firebird consistency check (partner index description not found (175), file: idx.cpp line: 209)

CSPROG Thu Dec 14 20:49:31 2017
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
Error while trying to write to file
Неверный дескриптор.

CSPROG Thu Dec 14 20:49:31 2017
Database: C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
Error while trying to write to file
Неверный дескриптор.

CSPROG Thu Dec 14 20:49:31 2017
Database: C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
Error while trying to write to file
Неверный дескриптор.

CSPROG Thu Dec 14 20:49:31 2017
INET/inet_error: read errno = 10054, server host = localhost, address = 127.0.0.1/3400

CSPROG Thu Dec 14 20:49:31 2017
REMOTE INTERFACE/gds__detach: Unsuccesful detach from database.
Uncommitted work may have been lost.
Error writing data to the connection.
send_packet/send

CSPROG Thu Dec 14 20:49:31 2017
setsockopt: error setting IPV6_V6ONLY to 0

=>

Create following script:

shell del C:\MIX\firebird\QA\fbt-repo\tmp\c2284.fdb 2>nul;
create database 'localhost:C:\MIX\firebird\QA\fbt-repo\tmp\c2284.fdb' user 'SYSDBA' password 'masterkey';

recreate table test_cs__detail(x int);
recreate table test_cs__master(x int);
commit;

set autoddl off;
recreate table test_cs__master (
str_pk varchar(32) character set UTF8 not null, --------------------- [ 1 ]
primary key (str_pk) using index test_s_master_pk
);

recreate table test_cs__detail (
str_pk varchar(32) character set WIN1251 not null, ------------------ [ 2 ]
foreign key (str_pk) references test_cs__master (str_pk)
);

set echo on;

commit;
rollback;

Console output:

ISQL Version: WI-V3.0.3.32854 Firebird 3.0
Server version:
WI-V3.0.3.32854 Firebird 3.0
WI-V3.0.3.32854 Firebird 3.0/tcp (csprog)/P15:C
WI-V3.0.3.32854 Firebird 3.0/tcp (csprog)/P15:C

commit;
Statement failed, SQLSTATE = 08001
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
-Error while trying to write to file
-invalid descriptor // in national codepage
After line 19 in file crash-on-pk-fk-with-diff-cset.sql
rollback;
Statement failed, SQLSTATE = XX000
internal Firebird consistency check (can't continue after bugcheck)
After line 21 in file crash-on-pk-fk-with-diff-cset.sql
Statement failed, SQLSTATE = XX000
internal Firebird consistency check (can't continue after bugcheck)
After line 21 in file crash-on-pk-fk-with-diff-cset.sql

Note:
1. Both tables have to be created BEFORE 'recreate table' statement, i.e. they must already exist;
2. Charsets in PK and FK fields differ.

PS.

I thought that this bug is related to CORE5677 or CORE2284, but after discussion with Vlad it was decided to create new ticket.
The same result on WI-V2.5.8.27083 and WI-T4.0.0.832 -- i.e. this bug is old enough.

firebird.log

CSPROG Thu Dec 14 20:49:31 2017
Database: C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB
internal Firebird consistency check (partner index description not found (175), file: idx.cpp line: 209)

CSPROG Thu Dec 14 20:49:31 2017
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
Error while trying to write to file
Неверный дескриптор.

CSPROG Thu Dec 14 20:49:31 2017
Database: C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
Error while trying to write to file
Неверный дескриптор.

CSPROG Thu Dec 14 20:49:31 2017
Database: C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB
I/O error during "WriteFile" operation for file "C:\MIX\FIREBIRD\QA\FBT-REPO\TMP\C2284.FDB"
Error while trying to write to file
Неверный дескриптор.

CSPROG Thu Dec 14 20:49:31 2017
INET/inet_error: read errno = 10054, server host = localhost, address = 127.0.0.1/3400

CSPROG Thu Dec 14 20:49:31 2017
REMOTE INTERFACE/gds__detach: Unsuccesful detach from database.
Uncommitted work may have been lost.
Error writing data to the connection.
send_packet/send

CSPROG Thu Dec 14 20:49:31 2017
setsockopt: error setting IPV6_V6ONLY to 0