One of the most common error a user encounters while updating is Problem with MergeList. The error could be encountered while using both Ubuntu Update Manager and using the sudo apt-get update in terminal. The complete error looks something like this:
E:Encountered a section with no Package: header, E:Problem with MergeList /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_precise_universe_binary-i386_Packages, E:The package lists or status file could not be parsed or opened.
The one shot solution of this problem is to run the following two commands, one by one, in the terminal (Ctrl+Alt+T):
sudo rm -r /var/lib/apt/lists/*
sudo apt-get clean && sudo apt-get update
Voila! That should solve the “problem with merge list” error. In other frequent Ubuntu update errors, one is Failed to download repository information. You may want to check them as well. Enjoy Ubuntu :)