500 Internal Server Error in OJS 3.2.1.1

Hey. We are using OJS version 3.2.1.1. Recently we were unable to download our files in OJS. When we want to download MS Word files in the journal dashboard, we face this error “500 Internal Server Error”. Also, when we want to download a published article from a journal website, we face another error "pdf file cannot be downloaded. I took a snapshot of this issue in the following image. Can you help me solve this problem?
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Hi @Sisfokomtek_Journal
show the php log please