Oracle Apex 4.2 custom file download error 404 Not Found or 403 Forbidden - blob

Question

I'am using Oracle Apex and I have a form to upload and store a file in a table via wwv_flow_files
In order to download the file I am using the procedure download_my_file
When I try to click the link and download the error 404 is raised
My environment is
Application Express 4.2.6.00.03
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
Oracle Rest Data Service 3.0.9.348.07.16
Thanks to any suggestion or advice
EDIT:
I check the stored procedure in Apex going Home->SQL Workshop->SQL Commands
If I copy and paste the code and instead of the parameter I use a known ID the execution is successful.
With the syntax download_my_file?p_file=#ID# url is
http://myhost:8080/ords/download_my_file?p_file=24255
the error 404 Not found is raised.
With the syntax #OWNER#.download_my_file?p_file=#ID# url is
http://myhost:8080/ords/mypdb.download_my_file?p_file=24255
the error 403 Forbidden is raised.
EDIT 2 : as requested here is the procedure
PROCEDURE download_my_file(p_file in number) AS
v_mime VARCHAR2(48);
v_length NUMBER;
v_file_name VARCHAR2(2000);
Lob_loc BLOB;
BEGIN
SELECT files_mime_type, files_content, files_name, dbms_lob.getlength(files_content)
INTO v_mime,lob_loc,v_file_name,v_length
FROM pub_db0files
WHERE files_id = p_file;
--
-- set up HTTP header
--
-- use an NVL around the mime type and
-- if it is a null set it to application/octect
-- application/octect may launch a download window from windows
owa_util.mime_header( nvl(v_mime,'application/octet'), FALSE );
-- set the size so the browser knows how much to download
htp.p('Content-length: ' || v_length);
-- the filename will be used by the browser if the users does a save as
htp.p('Content-Disposition: attachment; filename="'||replace(replace(substr(v_file_name,instr(v_file_name,'/')+1),chr(10),null),chr(13),null)|| '"');
-- close the headers
owa_util.http_header_close;
-- download the BLOB
wpg_docload.download_file( Lob_loc );
end download_my_file;

Answer 1

According to documentation «Fusion Middleware User's Guide for mod_plsql» regarding to wpg_docload.download_file we have to «add the line WindowsFileConversion Off to DAD entry.
Open the file ORACLE_INSTANCE\config\OHS\ohs1\mod_plsql\dads.conf.
Locate the DAD used to access the application.
Add the line WindowsFileConversion Off to this DAD entry.
Save the file.
Restart Oracle HTTP Server.
If you do not update the DAD configuration, you will experience failures while downloading documents which contain 0x5c in the filename. For example:
In Oracle Portal, you will see the download error:
Error: Document not found (WWC-46000)
When using mod_plsql against your own PL/SQL application, file downloads will result in the error:
HTTP-404 Not Found
https://docs.oracle.com/cd/E28280_01/portal.1111/e12041/concept.htm#YPMOD001