First, make sure an Office app isn't open (I like to set such policies to run at login in order to avoid this). The other thing I find is that almost all but the smallest packages will error out unless cached first.
So, in the JSS web interface, edit the policy so that under Packages, the package you're adding should be designated to Cache, not install. Then create another policy to install that cached package (I set this to run at login).
It might seem like unnecessary work, but it's nice in that you can set the caching policy to run via trigger15. It just copies the package to the local computer, so it can be run whenever, nobody is disturbed. Throughout the day, everyone gets the package saved nice and local. Then the install policy takes it from there whenever the user logs in, and actually installs the update.
Are other packages deploying and installing as you'd expect? How did you create your original Office 2011 deployment? Are you trying to simply deploy MS' own 14.3.1 .mpkg or did you do something different?
Do you have HTTP enabled, or are you using afp or smb? Is your server local?
FWIW I started deploying 14.3.1 this morning and so far it's been fine, by following most of the above advice - add the original .mpkg to Casper Admin, don't use HTTP, cache then install, run at startup, run Recon to note the new app version.
I have exactly as Michael suggested. Caching and staging the package but I still cannot get the update to execute!
What file should I have imported into Composer? Office2011-1431UpdateEN.dmg from: http://www.microsoft.com/en-us/download/details.aspx?id=36540? Or the update.pkg inside of that .dmg. Either way I have tried importing both to Composer/Admin. When I execute either package after staging, it completes with no errors but Office is still at 14.3.2....
I assume you mean 14.2.3 in your last line.
You want the pkg inside the dmg. You don't need Composer at all. Just upload the pkg inside the dmg from Microsoft as is to Casper Admin and save it.
So, with that pkg uploaded to Casper Admin and saved, set a policy to cache it via the trigger15. Then set another policy, triggered at login, to install the cached update.
It will install at any users' login. If another user is logged in and has an Office app or a browser open, it will fail. Make sure you're not getting caught up on something like that.
That's what should work. Confirm your workflow. If you're still not having success, test the pkg file on another computer if you can, by updating with it manually. Let us know if the manual update works and post the policy log.