Download from web server to iPad fails

[macdoggie]

I've been having a problem downloading pdfs from Calibre server via the web server using an iPad or iPhone (any browser). Up to 2.85 it worked great but since v3 it has not worked. I can get to the Calibre library fine and select a book. But when I try to download a pdf, it says "Safari cannot open the page because the connection was lost." There is no problem if it's an ePub. It doesn't matter if I'm inside my LAN or coming in from outside.

The server error log says (x's in ip address are mine):

"Error in SSL handshake, terminating connection: sendfile() failed to write any bytes to the socket
Unhandled exception in state: State: write_buf Client: 142.xxx.xx.xxx:61901 Request: GET /get/PDF/4523/Calibre HTTP/1.1
Traceback (most recent call last):
File "site-packages/calibre/srv/loop.py", line 565, in tick
File "site-packages/calibre/srv/http_response.py", line 572, in write_buf
File "site-packages/calibre/srv/http_response.py", line 388, in write
IOError: sendfile() failed to write any bytes to the socket

Error in SSL handshake, terminating connection: sendfile() failed to write any bytes to the socket"

Anyone have any thoughts on what is going wrong here? I'm stuck at 2.85 because I use this feature a lot.

Thanks!

[kovidgoyal]

1) What version of iOS and calirbe are these?

2) Are you using authentication? If so does it work without auth?

3) Does it work if you turn off SSL?

[macdoggie]

Hi
1) iOS 10.3.3, Calibre 3.7
2) Doesn't work either way
3) No
It's odd as ePubs almost always work but no success with PDFs.

[kovidgoyal]

What OS are you running calibre itself on? One more thing to try is turning off sendfile in the server settings (it's called zero copy file transfers).

[macdoggie]

Turning off zero copy transfer did the trick! Works now! Thanks so much!
It is on El Capitan.