FYI, I was able to access the first & second Saturday Evening Post link just now. Also the first book linked, Vida de Miguel de Cervantes Saavedra. Only ones I tried.
Found this post after getting the same "sry" page when trying to access IA.
The URL here is "web.archive.org/sry", which I suspect is always an error page; the question is what parts of the Internet Archive are currently redirecting to that page at any given moment.
I can confirm that the Internet Archive's whole archived-books collection was throwing errors for me yesterday (2025-11-19), and today, while it's ostensibly back up, certain tranches of material are no longer available. For example, these six issues of the Saturday Evening Post from October–November 1925 are no longer available. (I focus on these because they're the ones in which John Philip Sousa's memoir "Keeping Time" was serialized, so I have their URLs handy. I suspect that there's nothing special about these six and really the entire collection of the Saturday Evening Post is lost.)
Also these books which existed as recently as a year ago (detected by following hyperlinks from some of my transcribed works: I'd say no more than 1 in 10 is lost now, but still, it's disturbing that any are lost):
Archived-book searches right now (2025-11-20 about 12:30pm New York time) are failing with "Error details: backend_request search: The search backend encountered an exception (the FTS API request failed, the error reported was: HTTP 502)".
Reports of as-yet-unexplained losses in various areas of the archive:
Found this post after getting the same "sry" page when trying to access IA.