ORA-06502: PL/SQL: numeric or value error when calling PL/SQL procedure via dblink

Suppose we've got 2 Oracle databases connected via db link : client db and server db. On the client database the PL/SQL procedure (from the package) calls another procedure via database link (from package on the server database) and saves the result into a cursor (which is also declared via the same database link). Next the result is processed and data is delivered to the application.

Out of the sudden, an application started to get the error 6502 sometimes. As it's figured out the cause laid in the length of varchar2 variable (let's call it 'a'). So, 'a' is declared varchar2 (100) variable (in bytes) inside a pl/sql procedure on the client side. It gets data via database link from the cursor (declared via database link as I said before), created on the server side (the corresponding column also has varchar2 (100) datatype (in bytes)). 

It seems when client database gets the value of the this column in language different from English it internally converts it into client database characterset (from server database characterset - CL8MSWIN1251 to AL32UTF8 - characterset of client database). When converted value's length is greater then 100 bytes - the error ORA-06502 is arising. At this point increasing variable length (to 1000) fixed the issue. 

I hope you were able to comprehend the above ;-) Good Luck !!!

PS: simplified version of the client procedure :

PACKAGE BODY package_body AS
c_num varchar2(30);
FUNCTION getfullinfo(c VARCHAR2,date_from VARCHAR2,date_to VARCHAR2,flag NUMBER DEFAULT 0, cr NUMBER DEFAULT 0, megat NUMBER DEFAULT 0) RETURN curstype
IS
curs cursType;
recTableremote server_user.server_package.table_type@db_link;
recTablelocal local_user.local_package.table_type;
rec local_user.local_package.record_type;
BEGIN

recTablelocal := {initializing the type} ;
server_user.server_package.procedure@db_link(c, date_from, date_to, flag, cr, megat, recTableremote);
 

for i in 1 .. recTableremote.count
loop
rec.row_numb :=recTableremote(i).row_numb;
...