I don’t get an error message, but if I try to update the site files nothing happens. I tried multiple ways, like FTP or the File Manager, but the only thing that change is the HTML file. The CSS it’s like invisible.
Try using an incognito browser session to check your site. Ctrl f5 also works on most browsers.
Finally for CSS specifically, in your html you can add a version number to the CSS like this
Style.css?v=12345678
Then when you update the CSS, you update the version number in your html and it’ll force your browser to reload it rather than using the cached CSS from a previous visit
to your pages. This will force the browser to reload the page every visit, rather than caching the page. However, this could increase the hits\entry processes on your page, by stopping the browser caching the page.