I am able to access the NIFI UI now. Actually the problem was with the IP address. When I check the Inet address in VM console it showed me 192.168.5.128 and I connected to the VM from Putty using this Ip address. In Putty, when I checked the Inet address it showed me 172.17.0.2 and NIFI log file was also saying that you can access the NIFI UI at 172.17.0.2:port/nifi. But it was not loading using 172.17.0.2 then I tried opening NIFI UI at 192.168.5.128 and it worked. Why it is so? In my opinion, NIFI UI should open at 172.17.0.2:port/nifi instead of 192.168.5.128:port/nifi ??