Connection Could not Be Established. Reason Unknown.

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Comments

  • Yuri_T
    Yuri_T Posts: 2,249 [Former Staff]

    Hi @Yoyo2 ,

    Thank you for your post.
    Could you please check if you are using the latest version of TeamViewer?
    This might help this situation.
    New version.png

    All the best,
    Yuri

    Former Japanese Community Moderator
  • Yoyo2
    Yoyo2 Posts: 2

    I updated the version of the computer and the issue is still the same.  It orginally was connecting well and suddenly the issue happened.

  • Yuri_T
    Yuri_T Posts: 2,249 [Former Staff]

    Hi @Yoyo2 ,

    Thank you for your reply.
    In this situation, it is difficult to find the exact reason without a logfile.

    However, you might be able to do the following checks:

    Your general setup

    • Is your Internet connection working?

    Did anything change on your IT setup

    • Can TeamViewer reach the Internet?
      • If not, please open Port 5938 for outgoing connections

    Did TeamViewer work just a few minutes ago

    • Did you check our Status page? 
      • Here we post updates about the current TeamViewer system status

    Operating system

    Hope this will be helpful.

    All the best,
    Yuri

    Former Japanese Community Moderator
  • louarkie
    louarkie Posts: 2

    I have this problem too.  Have unintalled/reinstalled several times & tried different versions.

  • Tatti
    Tatti Posts: 1
    Unable to establish connection reason unknown
  • JeanK
    JeanK Posts: 7,037 Community Manager 🌍

    Hello @Tatti

    Thank you for your message.

    Could you please tell us the operating systems you are using and their exact versions, and also the exact versions of TeamViewer that are installed on your devices?

    Cheers

    Jean

    Community Manager

  • brhuge
    brhuge Posts: 9

    @JeanK 

    Main: Mac OS Sierra 10.12.6 Team Viewer Version 14.3.4730
    Remote: Windows 10 Team Viewer Version 14.3.4730 

    I've tried the Remote on Numerous Different Versions of Windows inlucding WIndows 7, and  8 as well as all versions of windows 10. None of them work and all give the same error. The weird thing is if I choose Remote Control using windows authentication and enter the Windows user name and password I am able to connect just fine.

  • JeanK
    JeanK Posts: 7,037 Community Manager 🌍

    Hello @brhuge,

    Thank you for your message.

    I replied to your post here: Mac to PC Remote Computer "Unable To Connect Reason Unknown" Partner Still using an older version of TeamViewer

    Best,

    Jean

    Community Manager

  • louarkie
    louarkie Posts: 2

    Update - narrowed this down to MAC to MAC connections.  I can establish a PC to MAC connection (and visa versa), but MacBook Air to Macbook Pro (and visa versa) triggers the "Version out of date/Reason unknown" sequence of errors.  Does not seem to be TV version specific. MAC OS version is High Sierra 10.13.6 on both machines.  TeamViewer version are the same on the MACs - 12.0.139437.  Upgrading to TV 14 resolved the issue.  Both Macs could connect to each other.

    Anybody else see this behavior?

    Thanks

  • tk10935
    tk10935 Posts: 1

    I'm getting the same "reason unknow" message when I try to connect to my laptop from my iPad and the connection fails.  this just started happening in the last week.  Here is a TV suggestion to someone else having the same problem.   Can you tell me how to check and open the Port?  

    Can TeamViewer reach the Internet?

    • If not, please open Port 5938 for outgoing connections
  • alexlarigola
    alexlarigola Posts: 1

    Same problem here. Say needs to update but after give me same error. No ideea why. I use it maybe once a month the free version.

  • nickdhutchinson
    nickdhutchinson Posts: 1

    Both myself and the person I'm trying to offer remote help to are on version 14.7.1965 and I'm getting a 'reason unknown' error saying that the remote TeamViewer is running an old version. This isn't the case. Why am I getting this error?

  • sonofsmog
    sonofsmog Posts: 1

    Just installed TeamViewer 14.7.1965 on a Windows 10 client and host. I get the error:

    A connection could not be established: reason unknown

    followed immediately by:

    The remote TeamViewer is running and old version which is out of date.

    The message boxes pop up one on top of another. Both the client and host are current. Rebooting did not help.

     

  • JeanK
    JeanK Posts: 7,037 Community Manager 🌍

    Hello 

    Thank you for your message and sorry for the late reply.

    Have you tried to restart the TeamViewer service on both sides of the connection.

    Please restart the TeamViewer service:

    1. Run services.msc
    2. Right click TeamViewer 1X
    3. Restart

    It might solve the issue.

    I hope this could help. If not, do not hesitate to ask your questions here.

    Cheers,

    Jean

    Community Manager

  • JeanK
    JeanK Posts: 7,037 Community Manager 🌍

    Hello @Machinvert,

    Thank you for your message.

    You will find all the information you need about this topic in our thread here: Reasons Unknown Error

    I hope this could help. If not, do not hesitate to ask your questions here.

    Cheers,

    Jean

    Community Manager

  • ManishSharma12
    ManishSharma12 Posts: 1

    I am aslo facing the same problem. Can you please tell me how to resolve this,

  • uflidd
    uflidd Posts: 1

    same problem here

  • eduardacanunes
    eduardacanunes Posts: 1

    unable to connect reason unknown

  • ShankarPakuwal
    ShankarPakuwal Posts: 1

    I am unable to do remote saying connecting after that session terminated.

  • dlpastel
    dlpastel Posts: 3

    I am receiving Reason unknown when trying to connect to remote computers. A couple of them work but most do not connect.

    I went into my account and it said I had too many computers so I deleted probably 75 computers but it is still not working

  • Ying_Q
    Ying_Q Posts: 2,707 Moderator ☑

    Hi @dlpastel,

    Thank you for visiting the TeamViewer Community!

    Would you mind sharing how did you do the computer deletion, please? Was it on TeamViewer Computers & Contacts list or TeamViewer Management Console?

    The issue sounds related to Managed Devices and we suggest you check out Delete Devices in bulk if you would like to do the deletion on devices.

    Kindly let me know if the Community articles help you!

    Best,

    Ying_Q

    Community Moderator/中文社区管理员
  • DWFinger
    DWFinger Posts: 1

    This is the first reference I have ever found as to how to resolve the Can't Connect Unknown Reason for TeamViewer 12. Everywhere else I saw an instruction to uninstall or upgrade to the latest version, but those never worked even when scrubbing the Registry and leftover files with Revo Uninstaller. In sifting through the Management Console I happened to notice that I had exceeded the number of deployments, but there was no indication that this would result in an inability to connect to newer deployments of TeamViewer Host (Quick Support was oddly unaffected). I cleaned up my deployments to get well under the number that my license supports and BAM! my Hosts could now be connected to.

    I know I am on an older version, but the messaging and what I found on a web search was completely wrong (uninstall/reinstall, upgrade to the latest version, etc.), and I could have been spared hours of frustration if somewhere it was noted that exceeding the number of deployments would result in newer installations of Host not being able to be connected with the cryptic "Unknown Reason" error.

  • yeskou
    yeskou Posts: 4

    Hi all,

    when I try to connect to my computer with unattended access I got this error message :

    QuickConnect Denied Reason: Unknown issue


    Anyone have an Idea about it ?

    TV issue.png


  • DigenPatel
    DigenPatel Posts: 1
    edited March 2023

    I was also getting the same error . I have installed the latest Team viewer version . Now I am able to connect to remote pc . So please install the latest version on both client and remote machine.

    first try with client pc and check you are able to connect or not. if not then install the latest version on remote pc.


    image.png


  • yeskou
    yeskou Posts: 4

    thanks for the answer, but even with the latest version,the issue persist

  • traduct
    traduct Posts: 4

    I have the exact same problem (I'm also on the latest version of Teamviewer)

  • that1crzywhtguy
    that1crzywhtguy Posts: 1

    Anybody figure this out yet? I'm having the same issue (also on the latest version).

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