Limesurvey disconnect and don't let users validate there forms.
LimeSurvey Version 2.59.1+170116
MYSQL v.5.5


Extract from log file

[Mon Apr 24 10:13:53 2017] [error] [client 193.49...] [host survey.docinfos.fr] (103)Software caused connection abort: Failed to flush CGI output to client
[Mon Apr 24 10:22:10 2017] [error] [client 193.49...] [host survey.docinfos.fr] (104)Connection reset by peer: Error reading request entity data, referer: survey.docinfos.fr/index.php/684636
[Mon Apr 24 09:59:55 2017] [error] [client 195.83...] [host survey.docinfos.fr] (104)Connection reset by peer: Error reading request entity data, referer: survey.docinfos.fr/index.php/684636
[Mon Apr 24 10:28:01 2017] [error] [client 162.38....] [host survey.docinfos.fr] (103)Software caused connection abort: Failed to flush CGI output to client
[Mon Apr 24 10:47:04 2017] [error] [client 134.59....] [host survey.docinfos.fr] (103)Software caused connection abort: Failed to flush CGI output to client
[Mon Apr 24 10:56:00 2017] [error] [client 195.221....] [host survey.docinfos.fr] (103)Software caused connection abort: Failed to flush CGI output to client

Hi,

that could be caused by any kind of server-side issues.
I would bet it is either a memory limitation or a no space on the hard disk, or permission issues.
Always a good idea is also to update to the latest version first, to see if it is resolved in a later version. (though I could not think of any related recent bug).

Need the CGI log : reason why is disconnect

Google: "Software caused connection abort Failed to flush CGI output to client"

First result:
forum.alsacreations.com/topic-20-75224-1...riptmalveillant.html

The problem is resolved. I had to update my mysql version.

Best