Missing Pdf file

Guys i have a serious proble. I have a website Voyage AMS. It has 3 OJS journal on sub domains. For the last 2-3 days I m unable to open any pdf and it says Missing pdf file. First I thought I was hacked but its happening on every OJS website inside it. Plz help me imma share you the links of the websites.

this is happening on every pdf file in my ojs website.
Plz help me

https://vjebr.voyageams.com/index.php/vjebr/index (Ojs 3.3.0.13)
This above website also shows this error.

https://vjes.voyageams.com/index.php/vjes/index (ojs 3.3.0.8)
https://vjsre.voyageams.com/index.php/vjsre/index (ojs 3.4.0.4)

Someone plz help me with this