Unable to attach to specified device

Article:TECH41502  |  Created: 2009-02-24  |  Updated: 2012-06-06  |  Article URL http://www.symantec.com/docs/TECH41502
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Article Type
Technical Solution




While attempting to initiate a Remote Control session, the following error appears:


pcAnywhere No Connection
Communications error
Unable to attach to specified device


There are multiple causes for this error to appear.

If a previous version of pcAnywhere is installed, then the reason for the error "Unable to attach to specified device" is typically one of the following:

  • the Symantec pcAnywhere Host Service is not running on the host computer
  • the pcAnywhere host is configured to run on a non-default port (a custom host data port is set in the pcAnywhere Settings policy or host file)
  • there is a networking issue which prevents access from the remote computer to the listening port of the host computer (TCP 5631 by default).  For example, a router, switch or firewall is blocking traffic to the port
  • traffic to the listening port on the host computer is blocked a software firewall (such as the Windows Firewall)
  • there is a conflict between Remote Desktop (RDP) and pcAnywhere such that they cannot be used simultaneously
  • the pcAnywhere Thin Host was deployed to a computer where the pcAnywhere Agent was already running

If pcAnywhere has been upgraded to the new release, pcAnywhere 12.5 SP4 or pcAnywhere Solution 12.6.7, then there are additional reasons for the "Unable to attach to specified device" to consider:

  • the remote version of pcAnywhere is the latest, while the host is a previous version (the new version is not backward compatible)
  • the remote and host encryption levels don't match. 
  • there is a pcAnywhere Solution 12.6.7 defect which prevents the Symantec pcAnywhere Host Service from running.
  • the remote user clicks "Deny" when prompted about the fingerprint




First, confirm whether the Symantec pcAnywhere Host Service is running on the host computer.  If not, set the Startup type of the service to Automatic, and attempt to Start the service.  If the service will not start, proceed with the troubleshooting steps below.

Verify what port the Symantec pcAnywhere Host program is using to listen for incoming requests, and that the remote pcAnywhere program is attempting to connect to the correct port.

To check for network issues, attempt to run the telnet command to the host computer and specify the correct port in the following format:

telnet <computername> <port>

For additional information about the telnet command, open "How to use Telnet to test TCP connections" from the Related Articles section below.  Correct all firewall issues such as routing, blocked ports and port-forwarding.


If RDP has been used to connect to the host computer, it may have left the "Symantec pcAnywhere Host Service" in an unstable state.  The solution is to avoid connecting to a computer with RDP while the "Symantec PCAnywhere Host Service" is Started.  To avoid this, either do not use RDP once pcAnywhere is installed, or set the "Startup type" of the "Symantec PCAnywhere Host Service" to Disabled.  If you set the Startup type to Disabled, then it will be necessary to remotely start the service prior to making a connection via pcAnywhere.

Also note that the pcAnywhere host service cannot be restarted via RDP.  For more information, click the link in the Related Articles section below for the article entitled 'Error: "The host cannot run in a remote terminal services session. Please run the host locally at the server."'

If you have upgraded to the new release, pcAnywhere 12.5 SP4 or pcAnywhere Solution 12.6.7

  • Ensure that both remote and host programs have the new version installed, and that they are both configured for the same encryption level. 
  • pcA QuickConnect can only use AES256.  If using pcA QuickConnect as the remote program, then the Encryption level must be set to AES256 in the Host Properties (or in the pcAnywhere Setttings policy if using pcAnywhere Solution) in order for the connection to succeed.


Legacy ID


Article URL http://www.symantec.com/docs/TECH41502

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