Team Build TF42046: The Build Service used in the build process is not reachable

Team Build TF42046: The Build Service used in the build process is not reachable 

One of our customers report that Team Build suddenly stop working and shows TF42046 error...

In this case the service status was "stop", the account that runs the service was expired.

If you encounter the TF42046 error, you may want to make sure of a few things:

1. That Team Build is installed on the build machine. This can be found on the Team Foundation Server installation CD in the Build directory. Run setup to install Team Build
2. Make sure the Team Build Service is running. Open the services MMC snapin and look for Team Build Service. Make sure the service is running. Also note the account that the service runs as; you will need it for the next step
3. Make sure the Team Build Service account (from step 2) is in the “TFS Service Accounts” group. For more information see http://blogs.infosupport.com/raimondb/archive/2005/11/28/bbsvcacc.aspx
4. Make sure the designated Team Build port is listening and available thru any firewalls. By default, the port used is 9191. Open a command prompt on the build machine and run “netstat”. Make sure TCP port 9191 is listening. You may want to make sure The Team Build service has this port and not another application on the build server. Make sure this port is not blocked by the window’s firewall or any other firewall in you enterprise.
5. Make sure the paths defined in your PATH system variable do not have any invalid characters. This includes any “” around the paths. Part of the Team Foundation Build Client source code attempts to build the path to msbuild.exe using the paths defined in this environment variable. Unfortunately the exception that is thrown when the system attempt to call Path.Combine on a malformed path is masked by the misdirecting TF42046 error.
6. If all else fails, turn on verbose tracing by navigating to the build server’s build service install directory and uncomment the trace flags in the TeamBuildService.exe.config file. You can find this file at “<install drive>:\Program Files\Microsoft Visual Studio 8\Common7\IDE\PrivateAssemblies\”. You can verify this directory by checking the run directory listed in the properties window of the TeamBuildService found in the services snapin.