Tried same link as posted originally - Opera just can't open this link. After saved to disk, can be opened in Opera without problem. No third-party antivirus or similar cr*p here, Win Defender is active. Opera dev version.
Looking at traffic with fiddler, it seems that Opera requests PDF both in full (first request) and then in chunks and somehow it doesn't do it properly, at least server thinks so:
(part of Opera second request)
Range: bytes=3014656-3343126
(server response)
416 Requested Range Not Satisfiable
Looks like bug. I don't think that this behavior depends on PDF size (I just lately looked at quite big PDFs - 11MB or so, although performance was very poor), but on some server handling nuances of Opera requests.
