The redirect module prevents the system.private_file_download route from working. This route is accompanied by a inbound processor "path_processor.files" that alters the path and the request, moving everything after /system/files to a query argument. The redirect module calls the inbound processes very early and allows the request object to be altered while changes to the path are not propagated. This results in the router.route_provider no longer finding the system.private_file_download route.
The redirect module prevents the system.private_file_download route from working. This route is accompanied by a inbound processor "path_processor.files" that alters the path and the request, moving everything after /system/files to a query argument. The redirect module calls the inbound processes very early and allows the request object to be altered while changes to the path are not propagated. This results in the router.route_provider no longer finding the system.private_file_download route.