while adding invoice attachment in isupplier its throwing error You are trying to access a page that is no longer active. - The referring page may have come from a previous session. Please select Home to proceed.
not saying that this will solve your problem
but does your attachment extention is in those 2 table
select * from fnd_mime_types_tl where file_format_code in ('DOC','TXT','JPG','XLS','PDF','JPEG','MSG','DOCX','XLSX','ZIP');
select * from fnd_mime_types where upper(file_ext) in ('DOC','TXT','JPG','XLS','PDF','JPEG','MSG','DOCX','XLSX','ZIP');
also check for allow_file_upload in fnd_mime_types