Instead of initially using the Client Deployment Wizard, you can also put 32bit and 64bit Install Packages in the group that you are trying to upgrade. SEPM will then attempt to auto-upgrade any clients in that group that are using a prior version. Give it some time and the clients should be able to heartbeat into the SEPM and upgrade automatically. Any clients that are left behind, you can then try using the CDW perhaps by a specific IP address or machine name to begin with.

Solution

 - Access the install packages tab and remove the upgrade packages that has been added;

- Add the packages again;

- Set new period of time time for SEPM to provide the upgrade packages to the clients.

If the DNS error is shown in SylinkMonitor, try to add the SEPM's IP address and name into hosts file as workaround but also verify if the DNS server registries are correctly configured.

To upgrade clients by using AutoUpgrade

1. In the Symantec Endpoint Protection Manager console, click Admin.

2. Click Install Packages.

3. Under Tasks, click Upgrade Clients with Package.

4. In the Upgrade Groups Wizard panel, click Next.

5. In the Select Client Install Package panel, select the appropriate client installation package, and then click Next.

6. In the Specify Groups panel, select the groups that contain the client computers that you want to upgrade, and then click Next.

7. In the Package Upgrade Settings panel, select Download from the management server.

   You can optionally stage and select a package on a Web server.

8. Click Upgrade Settings.

9. On the General tab, select Maintain existing client features when updating.

   You can optionally add or remove features when upgrading.

10. Optionally, on the Notification tab, customize the user notification settings. You can customize the message that is displayed on the client computer during the upgrade. You can also allow the user to postpone the upgrade by an amount you specify.

    For more information about schedule and notification settings, click Help.

11. Click OK.

12. In the Upgrade Groups Wizard Complete panel, click Next.

13. Click Finish.

Hi,

There is public KB is available on same.

Upgrading clients by using AutoUpgrade 

http://www.symantec.com/docs/TECH96789

You will have to make sure all the clients are online, offline clients will receive new package once they become online.

You are not able to upgrade clients by deploying packages & Suppose if auto upgrade also couldn't help then further troubleshooting would required.

Had the same issue when upgrading from 11.x to 12.x on certain workstations.  The setup.exe would run, but no change would be made.  I went to the local machine and checked the event logs, and found that the msi would error out if Windows was "pending a reboot" from a Windows Update.  After manually installing all updates and rebooting, the setup.exe would run successfully.  This was reproduced on about 4 machines in my environment.

HTH

AlexK101 

Very good point mentioned in his post. May help you.

Thank you everyone, I already knew how to do auto upgrade procedure, but it was seemingly not working etc. Appears more patience is called for etc. We don't have any PCs configured to do automatic Windows Update, so that issue doesn't apply to us. Will continue waiting on the clients and continue observation etc.

Thank you, Tom