Error when trying to enable ufw logs on Ubuntu

I am trying to enable logs for ufw.

When I do sudo ufw status I get

Status: active

To                         Action      From
--                         ------      ----
53535                      ALLOW       Anywhere                  
9090                       ALLOW       Anywhere                  
1883                       ALLOW       Anywhere                  
22                         ALLOW       Anywhere                  
53535 (v6)                 ALLOW       Anywhere (v6)             
9090 (v6)                  ALLOW       Anywhere (v6)             
1883 (v6)                  ALLOW       Anywhere (v6)             
22 (v6)                    ALLOW       Anywhere (v6)             

Which is ok

Then I try to enable logs:

[root@artik log]# ufw logging on ERROR: Could not update running firewall

So I try to disable firewall, enable logging and restart ufw

[root@artik log]# ufw disable
Firewall stopped and disabled on system startup
[root@artik log]# ufw logging on
Logging enabled
[root@artik log]# ufw enable 
ERROR: problem running ufw-init
iptables-restore: line 43 failed
ip6tables-restore: line 138 failed
ip6tables-restore: line 43 failed

Problem running '/etc/ufw/user.rules'
Problem running '/etc/ufw/before6.rules'
Problem running '/etc/ufw/user6.rules'

Why is it happening ? What should I do to fix it?

Here is how I fixed it

Disable IPV6 in /etc/default/ufw

change IPV6=yes to IPV6=no

Logs was giving me errors, so I disabled it

ufw logging off

Then I configured the firewall

ufw default allow outgoing 
ufw default deny incoming 
ufw allow out on tun0
ufw allow in on tun0
ufw enable

Hope it helps others!