link icon
Ask The Community

Teamviewer12 on Xubuntu fails to connect after security upgrades

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: 184 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.
  • 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.

Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!