sudo apt-get install metasploit-framework
if not
1. version too old
sudo apt-get update
sudo apt-get dist-upgrade
2. The anti-virus software is deleted, turn off antivirus software
sudo apt-get install metasploit-framework
if not
1. version too old
sudo apt-get update
sudo apt-get dist-upgrade
2. The anti-virus software is deleted, turn off antivirus software