At some point between Apex 2 and 3 Oracle decided tighten the security on calling stored procedures. I had a procedure that was being used to download documents from the database to the browser. This worked fine in Apex 2, but was broken after the upgrade. Upon clicking on the document link I was receiving a "Forbidden" message. This indicated a... At some point between Apex 2 and 3 Oracle decided tighten the security on calling stored procedures. I had a procedure that was being used to download documents from the database to the browser. This worked fine in Apex 2, but was broken after the upgrade. Upon clicking on the document link I was receiving a "Forbidden" message. This indicated a security problem. After some searching I came across others talking about a function that effectively allows you to "register" procedures that you would like allow to be called via the PL/SQL gateway. This procedure is in the APEX schema and is named wwv_flow_epg_include_mod_local.
I needed to comment out the return false at the beginning of the function and add the name of the procedure I wanted to allow calling to the list.
i.e.
if upper(procedure_name) in (
'QUANT.APEX_DOWNLOAD_NOTEBOOK_ENTRY') then
return TRUE;
else
return FALSE;
end if;

Read more http://billennis-ssts.blogspot.com/2009/08/wwvflowepgincludemodlocal.html