File link not working?

Question

Yii

Hello, I am facing a problem that I have never encountered before. I provide a link to the file:

<li><a href="/files/catalog.pdf">Каталог оборудования</a></li>

the file definitely exists and is located at this address. But when I click on the link, the page takes a long time to load, and then an error appears: Unable to access the site
This error occurs only in pdf files!
Site on yii2