Address already in use: Solution

lsof -i tcp:80

COMMAND  PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
python  1440 root    3u  IPv4  21915      0t0  TCP *:http (LISTEN)

sudo kill 1440
[*] exec: sudo kill 1440

msf exploit(multi/handler) > lsof -i tcp:80
[*] exec: lsof -i tcp:80

msf exploit(multi/handler) > [7]   Killed