[Topic edited by moderator for clarity.]
Hi, now that I've updated the site, I see a window in my browser with the text: Some files on the server may be missing or incorrect. Clear your browser's cache and try again. if the problem persists, contact the author of the site.
The window is also displayed to all other visitors to the website. I checked the website, everything is fine. After the last update (March 2020), this has not happened until now. Could you give me an advice please?