How to fix "Problem with MergeList /var/lib/apt/lists/"
Sometimes, and more often, an update on RaspberryPi hangs with: "Problem with MergeList ..." sudo mv /var/lib/apt/extended_states /var/lib/apt/extended_states_tmp && rm -rf /var/lib/apt/lists/* -vf && sudo apt-get update solves the issue.