Can't view and download pdf article in OJS 3.1.0

I have upgrade the OJS 3.1.0 but have problems with PDF files. In PDF viewer file is not viewed
and also using the link I can’t download the file

Hi @rustan_amarullah

What OJS version did you use earlier?
Was the upgrade successful i.e. without any warnings/errors?


problem solved, there is problem in the permission folder

i upgrade the OJS from 2.4.8 version to 3.1.0