Event ID 16 — WUA Server Connectivity

Updated: December 13, 2007

Applies To: Windows Server 2008

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The Windows Update Agent runs on client computers and must connect to either one of the following:

  • A Windows Update server running Windows Server Update Services (WSUS) on the corporate network.
  • The Windows Update/Microsoft Update (WU/MU) service publicly available from Microsoft.

If connectivity fails, the Windows Update Agent cannot communicate with the Windows Update server or to the WU/MU service.

Event Details

Product: Windows Operating System
ID: 16
Source: Microsoft-Windows-WindowsUpdateClient
Version: 7.0
Symbolic Name: VISTA_MSG_UNABLE_TO_CONNECT
Message: Unable to connect: Windows is unable to connect to the Automatic Updates service and therefore cannot download and install updates according to the set schedule. Windows will continue to try to establish a connection.

Diagnose

Diagnose

This error might be caused by one of the following conditions:

  •   The proxy server settings are incorrect.
  •   Proxy authentication problems have occurred.
  •   The connection between the client computer and the proxy server is broken.

The proxy server settings are incorrect

     To determine if there is a problem with server connectivity:

  • Check Internet Explorer proxy server settings and ensure that you are communicating with the expected proxy server. To check for proxy server settings, open Internet Explorer. On the Tools menu, click Internet options, click Connections, click the network connection being used, and click Settings.
  • Check if the proxy server is set up to use the correct settings.
  • If Automatically detect settings is selected in Internet Explorer proxy settings, check the WinHTTP proxy settings. If you are running Windows Vista, open the Command Prompt window and type netsh winhttp show proxy at the command prompt. If you are running Windows XP, open the Command Prompt window and type proxycfg.

If the proxy settings are not set correctly, see the section titled "Check proxy server settings."

Proxy authentication problems have occurred

After the proxy settings have been checked for the correct settings, check if the authentication is correct. To correct authentication problems, see the section titled "Correct proxy authentication problems".

The connection between the client computer and the proxy server is broken

  • At the command prompt, type ping IP_address where IP_address is the address of the proxy server.
  • If the ping was not successful, see the section titled "Check connection between client computer and proxy server."

Resolve

Check proxy server settings

The Microsoft Windows Update client program requires Windows HTTP Services (WinHTTP) to scan for available updates. In addition, the Windows Update client uses Background Intelligent Transfer Service (BITS) to download these updates. WinHTTP and BITS run independently of Microsoft Internet Explorer. Both these services must be able to detect the proxy server or proxy servers that are available in your particular environment.

If the Windows Update Agent fails to communicate with the server, first check Internet Explorer proxy settings and ensure you are communicating with the expected proxy server.

To check for proxy settings:

  • Open Internet Explorer. Click Tools, click Internet Options, click Connections, choose the network settings, click LAN settings, and type the correct settings for the proxy server.

Check connection between client computer and proxy server

If Windows Update Agent fails to communicate with the server, you can check the connection manually by running the wuauclt.exe utility. Wuauclt is a background process that polls the Microsoft Update Web site for updates. Running wuauclt with the /detectnow switch instructs the program to check the server for updates immediately.

To check connection manually:

  1. Open the Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type wuauclt /detectnow, and then press ENTER.
  3. At the command prompt, type eventvwr.msc and press ENTER to open Event Viewer.

 

Correct proxy authentication problems

After the client computer has connected to the correct proxy server, it should be able to authenticate the user credentials.

To check that your client computer can connect to and authenticate the local proxy server: 

  1. Ensure that autodetect is selected in Internet Explorer: To check autodetect settings, open Internet Explorer, click Tools, click Internet Options, click Connections, choose the network settings, and click LAN settings. Ensure that the Automatically detect settings check box is selected.
  2. If autodetect is selected in Internet Explorer proxy settings, check WinHTTP proxy settings by following steps 3 and 4.
  3. If running Windows Vista, open the Command Prompt window and type netsh winhttp show proxy.
  4. If the proxy server is correct, retry detection by opening the Command Prompt window and typing wuapp.
  5. When you have ensured that you are connected to the correct proxy server, check that the correct credentials are being used.

Verify

To check the connection with the Windows Update server or Windows Server Update service, run the wuauclt.exe utility. If wuauclt.exe succeeds, Event ID 30 is added in Event Viewer.

To confirm that connectivity with the Windows Update server is working properly:

  1. Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
  2. Type wuauclt /detectnow, and then press ENTER.
  3. At the command prompt, type eventvwr.msc and press ENTER to open Event Viewer.
  4. To check if Event ID 30 is present:
    1. In the left panel of Event Viewer, click Application and Service Logs.
    2. Expand Microsoft, and then expand Windows.
    3. Click WindowsUpdateClient, and then click Operational.
    4. Check to see if Event ID 30 is present in the event list.

Related Management Information

WUA Server Connectivity

Windows Update

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