Cannot connect to server: EMPTY RESPONSE

General discussion about Zimbra Desktop.
sestores
Posts: 26
Joined: Thu Feb 26, 2015 9:40 am

Cannot connect to server: EMPTY RESPONSE

Postby sestores » Fri Apr 24, 2015 2:48 pm

I have several users running zimbra desktop (version 7.2.5) and most of them have no issues. We are connecting to a zimbra server (Version 8.6.0) running on CentOS in a VM.
I have had one user that has been getting this error occasionally: "Cannot connect to server". Clicking on the details shows "EMPTY RESPONSE"...
I can kill the zimbra process and re-launch it and everything is ok for a while, but then it happens again. Usually once or 2x a day.
This morning, I had one other user who had the same problem (so far just one time).


What should I be looking for?
This is causing me to pull my hair out. 



Dr_Agony
Posts: 1
Joined: Sat May 09, 2015 12:49 pm

Cannot connect to server: EMPTY RESPONSE

Postby Dr_Agony » Sat May 09, 2015 12:52 pm

I'm having the same issue. Except that my users aren't using the Zimbra Desktop, they're logging in on the Internet. Most of my users have no issues at. One of my users says it happens so often that he can't even use his email.

I'm running Zimbra 8.6.0_GA_1153.FOSS.



I haven't found any help online to this problem. Is there an answer out there?
Javier Garcia Alarcon
Posts: 38
Joined: Sat Dec 27, 2014 7:09 pm

Cannot connect to server: EMPTY RESPONSE

Postby Javier Garcia Alarcon » Wed May 27, 2015 9:28 am

Hello all. One of my customers have the same issue. Sometimes, not the same client, says that long response time to the server has been detected and cuts the connection.

Latency to the server is about 60ms, max imap copnnections are 400 (there are about 200) and we dont see any lost packet in the connection.

Any idea?

Best regards
Javier Garcia Alarcon
Posts: 38
Joined: Sat Dec 27, 2014 7:09 pm

Cannot connect to server: EMPTY RESPONSE

Postby Javier Garcia Alarcon » Wed May 27, 2015 9:29 am

Sorry, Centos 6.5 ZOS 8.6 Patch 2 12 Gb Ram 2 CPU DL 360
User avatar
jorgedlcruz
Zimbra Alumni
Zimbra Alumni
Posts: 2782
Joined: Thu May 22, 2014 4:47 pm

Cannot connect to server: EMPTY RESPONSE

Postby jorgedlcruz » Wed May 27, 2015 10:46 am

Hi Javier, guys,

The Zimbra Desktop 7.2.7 Release is in Beta and will be available pretty soon, let us know when is public if fix this problem.



Best regards
Jorge de la Cruz https://jorgedelacruz.es
Systems Engineer at Veeam Software https://www.veeam.com/
Javier Garcia Alarcon
Posts: 38
Joined: Sat Dec 27, 2014 7:09 pm

Cannot connect to server: EMPTY RESPONSE

Postby Javier Garcia Alarcon » Wed May 27, 2015 10:48 am

Hi Jorge... Bu this problem is, in my case, not only from client... webmail have issues too and some thunderbid gives similar messages... i am whitelisting ip in dosfilter to see if it's the problem...
Javier Garcia Alarcon
Posts: 38
Joined: Sat Dec 27, 2014 7:09 pm

Cannot connect to server: EMPTY RESPONSE

Postby Javier Garcia Alarcon » Wed May 27, 2015 10:52 am

I see...



2015-05-27 17:50:39.426:WARN:oejs.DoSFilter:qtp2047526627-9642:https://a.b.c.d:443/service/home/~/?auth=co&id=3313&part=8&t=1432741840665: DOS ALERT: Request rejected ip=a.b.c.d,session=1mfp9dt8048v41jomh21hq2wf4,user=null

2015-05-27 17:50:39.451:WARN:oejs.DoSFilter:qtp2047526627-9640:https://zimbraserverip:443/service/home/~/?auth=co&id=3313&part=2&t=1432741840638: DOS ALERT: Request rejected ip=zimbraserverip,session=1mfp9dt8048v41jomh21hq2wf4,user=null

2015-05-27 17:50:39.475:WARN:oejs.DoSFilter:qtp2047526627-9639:https://1zimbraserverip:443/service/home/~/?auth=co&id=3313&part=2&t=1432741840635: DOS ALERT: Request rejected ip=a.b.c.d,session=1mfp9dt8048v41jomh21hq2wf4,user=null

2015-05-27 17:50:39.476:WARN:oejs.DoSFilter:qtp2047526627-9643:https://zimbraserverip:443/service/home/~/?auth=co&id=3313&part=3&t=1432741840642: DOS ALERT: Request rejected ip=a.b.c.d,session=1mfp9dt8048v41jomh21hq2wf4,user=null
sestores
Posts: 26
Joined: Thu Feb 26, 2015 9:40 am

Cannot connect to server: EMPTY RESPONSE

Postby sestores » Fri May 29, 2015 10:19 am

Javier, I agree. I think we are only seeing this on the Desktop client because most of our users are using it.

I have read others with the same issue on the webmail client. Our webmail client only gets light usage.
Javier Garcia Alarcon
Posts: 38
Joined: Sat Dec 27, 2014 7:09 pm

Cannot connect to server: EMPTY RESPONSE

Postby Javier Garcia Alarcon » Fri May 29, 2015 11:15 am

Hi all

I ve changed Max Imap Sessions to a upper value and the problem does not dissapear but, after a log an documentation research i Think that perhaps is the DosFilter... why? well....Really the problem appears usually most times early in the morning and after lunch about 15 pm so I think that perhaps the trigger is the amount of new open sessions for time unit. Suddenly every people connect and DosFilter stop them from a number of connections in time unit. I ve changed this whitelisting the ip (a large number of sessions come from the same IP) in DosFilter and after two days i have no notices of new issues... i will wait a week and if the problem has dissapeared i will think that this is the origin. I will say you...
thenodemaster
Posts: 7
Joined: Fri Aug 21, 2015 2:13 pm

Cannot connect to server: EMPTY RESPONSE

Postby thenodemaster » Tue Sep 15, 2015 11:44 am

Pardon my question, but where do you find the Max IMAP Sessions option (path and config file)? I think this is what is happening with our server as well and would like to test that theory. Thanks!

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