Teamviewer12 on Xubuntu fails to connect after security upgrades

conoroneill Posts: 2 ✭✭

I have been successfully using Teamviewer 12 for a while on my Xubuntu laptop. I apply various security patches to my system as appropriate. Sometime in the last month or two, something has changed and now Teamviewer won't connect to its servers.

I am running Xubuntu 17.04, with teamviewer installed using teamviewer_12.0.76279_i386.deb

If I look at the logfile (/var/log/teamviewer12/TeamViewer12_Logfile), I see host lookup errors like these:

2017/08/22 16:30:49.450 17089 4127206208 S!! HttpRequestImpl::CurlFinished(): curl request failed: Couldn't resolve host name (6), Could not resolve host:
2017/08/22 16:30:49.450 17089 4127206208 S!! NetWatchdog: Port 80 proxy search failed! No working setting found. -- next log entries will be omitted --
2017/08/22 16:30:49.450 17089 4127206208 S! CKeepAliveClientClient::HandlePing(): ping failed
2017/08/22 16:30:49.451 17089 4127206208 S Activating Router carrier
2017/08/22 16:30:49.451 17089 4127206208 S CProcessCommandHandlerMasterConnect[3852]::CreateMasterConnect():, Connection 3852, proxy=''
2017/08/22 16:30:49.453 17089 4143991616 S!! HttpRequestImpl::CurlFinished(): curl request failed: Couldn't resolve host name (6), Could not resolve host:
2017/08/22 16:30:49.453 17089 4143991616 S! CProcessCommandHandlerMasterConnect[3852]::HandleMasterConnect(): MasterConnect to failed
2017/08/22 16:30:49.454 17089 4143991616 S!! LookUpDNS failed for, socket error = -3, Errorcode=11
2017/08/22 16:30:49.454 17089 4143991616 S!!!Connect to Master / failed!, Errorcode=11
2017/08/22 16:30:49.454 17089 4143991616 S!! CMasterConnectorAsio::HandleMasterResponseLogin(): MasterConnect failed. ErrorCode=10, Errorcode=11

I've googled around this; some people recommend restarting the daemon like this, but it doesn't help:

sudo teamviewer daemon restart

I've also tried uninstalling and re-installing the .deb file, but no progress.

Another thread has suggested adding the various hostnames into my /etc/hosts file. I have done this, and I get a slightly different set of errors, in that the system can now resolve the hostnames, but still cannot connect to the servers; error messages like these:

2017/08/22 17:06:41.191 22443 4135238464 S   CProcessCommandHandlerMasterConnect[2]::CreateMasterConnect():, Connection 2, proxy=''
2017/08/22 17:06:46.192 22443 4135238464 S CTcpConnectionBase[2]::HandleConnectTimeout(). Connect timed out to
2017/08/22 17:06:46.192 22443 4135238464 S! CProcessCommandHandlerMasterConnect[2]::HandleMasterConnect(): MasterConnect to failed
2017/08/22 17:06:46.192 22443 4135238464 S!!!Connect to Master / failed!
2017/08/22 17:06:46.193 22443 4135238464 S!! CMasterConnectorAsio::HandleMasterResponseLogin(): MasterConnect failed. ErrorCode=10
2017/08/22 17:06:46.193 22443 4135238464 S CTcpConnectionBase[2]::HandleConnect(): Connect failed to dest-ip with error 125 Operation canceled
2017/08/22 17:06:49.196 22443 4118453056 S Activating Router carrier

What else can I do to try to diagnose and fix this? I don't believe that my firewall is blocking any outgoing ports.

Many thanks for any help


  • ChristianCay
    ChristianCay Posts: 182 [Former Staff]

    Dear conoroneill,

    Thank you for your post.

    The reason for those errors is that TeamViewer is not able to reach our servers on port 5938.

    This can be caused by a firewall issue blocking outbound access to that port number.

    To correct this then please open your choice of a file editor and add the following line in the global.conf file that can be located here: /opt/teamviewer/config/global.conf

    First, stop the daemon with the command

    sudo teamviewer daemon stop

    Then add the following:

    [int32] AllowedConnectionProtocols = 3

    After this, please restart the TeamViewer daemon

    sudo teamviewer daemon start

    Hope this solution works for you.


    Best regards,


    Did my reply answer your question? Accept it as a solution to help others, Thanks.
  • conoroneill
    conoroneill Posts: 2 ✭✭

    Thank you for responding. Unfortunately, your advice didn't work for me, teamviewer still failed to connect even with

    [int32] AllowedConnectionProtocols = 3

    However, I have today upgraded my Ubuntu release from 17.04 to 17.10, and teamviewer is  now working again, even without the AllowedConnectionProtocols setting.

    I have to assume that there was some quirk in my DNS settings which conflicted with TeamViewer, but the upgrade to 17.10 has fixed this.

    Thank you for your help anyway.