I was getting this when I did the following:
l_session_info.set_attribute( render_context_portlet.g_roi_code_preference, null ) ;
This is because the procedure is overriden with multiple data types. When you give it a null it doesn’t know which of the overriden procedures you are calling and can’t resolve it.
Instead I put
l_session_info.set_attribute( render_context_portlet.g_roi_code_preference, ‘’ ) ;
and all was well. If you want it to go to a date type then you need to_date(’‘)… you get the idea.
The really strange thing is that ’’ is null for all other intents and purposes. You can’t get its length – all you get is null. But it seems to be a null with a varchar type.
You can’t say
if x = ‘’
then …
either. It always returns false because ’’ is null.