First of all, December 2013 CU download may be a challenge. In the download, there are 2 files. ubersrv.exe and ubersrv_1.cab. If for some reason, after extracting you have one file instead of two, don’t even try upgrading.
From Stefan Goßner’s post:
You will come to see that you need to install March 2013 PU first. That went pretty smoothly for me. But December 2013 CU did not.
After you made sure that you have both the exe and cab file, install them in your servers in the farm. However, when I ran SharePoint Product Config Wizard, I kept on getting the following message:
“Microsoft.SharePoint.PostSetupConfiguration.PostSetupConfigurationTaskException was thrown”
After a few restarts and pounding my head on the tables, enter the world of search. The following link came up:
In the above link it is advised that Product Config Wizard needs to be run as admin. However, that did not help me. So I started looking into another link referred in t he above:
Note that both the above links are for SharePoint 2010. However information is relevant to SharePoint 2013 also.
When I went through the stack exchange link, I noticed good old psconfig with wait and force parameter:
psconfig.exe -cmd upgrade b2b -wait -force
So I gave it a try. It did not work. However, the exception message changed. This time the message was:
OK, that is a progress!
I gave psconfig another couple of tries. In the last try, it pointed me to a specific database. It said it is not able to handle that database. Very good. I decided I will detach all content databases that I already upgraded from SharePoint 2010. That was a massive clue. Once that was done, I did a restart and ran SharePoint Product Configuration Wizard. And yay, success this time around!
Bottom-line is if you get stuck with exceptions after upgrade, depending on your farm, the solution may be different. So try various things and one of the solutions may work for you.