For about a month I have been getting bombarded with notifications to upgrade to Ubuntu 19.04 from 18.10, so I finally got around to do it only to find the "Upgrade" button in the software-updater did nothing.
So I started googling what needs to be done. Everything pointed me to update the installed software packages with
> sudo apt-get update && sudo apt-get upgrade
That seemed to return "0 newly installed, 0 to remove and 1 kept back". In this case it was libodbc1 was kept back, The libodbc1 package had to be force installed using the below command.
> sudo apt-get install libodbc1
Only after which the upgrade button in Ubuntu started working. At this point I've not been able to figure out why it was not upgraded the normal way but in case any one is in such a pickle where the Ubuntu upgrade button just closes the window and does not do anything, it more often than not has to do with updating packages. If there are any packages that are kept behind or not upgraded, they will have to be individually installed.