just delete ~/.cache/software-center/software-center-agent.db/ by opening a terminal (CTRL+ALT+T) and typing:
sudo rm -fr ~/.cache/software-center/software-center-agent.db/
just delete ~/.cache/ software- center/ software- center- agent.db/ by opening a terminal (CTRL+ALT+T) and typing:
sudo rm -fr ~/.cache/ software- center/ software- center- agent.db/