I get this error message, while the file uploaded fine. Very annoying.
Request from 2.7.118.246 via cp3064 cp3064, Varnish XID 322415563 Error: 503, Backend fetch failed at Sun, 09 Jan 2022 13:47:48 GMT
https://commons.wikimedia.org/wiki/File:Troismousquetaires_51_dumas.mp3 26 MB file, upload-by-url from IA
https://archive.org/download/trois_mousquetaires_0810_librivox/troismousquetaires_51_dumas.mp3
This happens regularly for files from 25 to 40 MB.