10

Not sure if this is worth reporting, but I clicked on this question in the HOT sidebar, and was met by an empty page with just the text "I/O error (head)":

<html>
  <head></head>
  <body>
    <pre style="word-wrap: break-word; white-space: pre-wrap;">I/O error (head)</pre>
  </body>
</html>

I can't reproduce it, but I also didn't see any existing questions on it, so I thought I'd bring it up.


Seemingly related, I just got a similar broken page when trying to view this question:

<html>
  <head></head>
  <body>
    <pre style="word-wrap: break-word; white-space: pre-wrap;">failed to connect to host</pre>
  </body>
</html>
1
  • Just had the same error when trying to post a comment.
    – rene
    Jul 5, 2019 at 19:55

1 Answer 1

2

I'm not suggesting that this question be closed as a duplicate of this question but it's the same error category, occurring several months ago. One file with such an error message is http1client.c on line #241. That's relevant if SE uses H2O Server. Also reported on The Tavern chat on Dec 18 2017.

Apparently it happens sporadically and only affects some people. If it continues, or others can confirm, it will provide more points in the log to check. It's useful to provide your local (or UTC) time, the people checking have access to any other information from your User Name; so other personal details won't be necessary (unless you're away from your usual access location, and had a single occurrence elsewhere).

7
  • They run IIS behind HAproxy if memory serves, with fastly as a CDN... Apr 4, 2019 at 2:46
  • 1
    I can confirm that I experienced it earlier today, but I can't provide any other useful information.
    – Mark
    Apr 4, 2019 at 3:02
  • In one of the links in my answer Shane mentions finding the error with as much/little information as was reported there. Fastly does use H2O, so my answer has supporting evidence. @Mark, if you do remember an approximate time that would be helpful, thanks for your report.
    – Rob
    Apr 4, 2019 at 3:08
  • @Rob 19:30 UTC yesterday, give or take half an hour (so, roughly 24 hours ago).
    – Mark
    Apr 4, 2019 at 19:54
  • @Rob: the page you link to shows Fastly supports the H2O project by providing free CDN services. I don't see any evidence that it uses H2O. Apr 5, 2019 at 8:18
  • 2
    @Rob: better evidence: fastly.com/blog/optimizing-http2-server-push-fastly :-) And this very thorough overview of the FT.com serving infra clears it for me: The normal Fastly stack consists of a two layer system, first they have a HTTP proxy called h2o used to manage TLS termination, and then we have a popular caching HTTP reverse proxy called Varnish. So H2O is used for TLS termination. Apr 5, 2019 at 8:35
  • @MartijnPieters Thanks. I upvoted your comment to credit you for the time and money you spent dealing with Jg's comment (whom didn't vote, just appeared to chime in). I've been quite busy this week.
    – Rob
    Apr 5, 2019 at 12:14

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