The Uncomplicated Firewall (UFW) is a powerful yet simple tool for managing iptables-based firewalls on Linux. However, sometimes users encounter an issue where UFW fails to start or enable properly. This guide will help you diagnose and fix the most common causes of the “ufw not starting” problem.
1. Check UFW Status
Before applying any fix, check whether UFW is active or disabled:
sudo ufw status verbose
If you see something like Status: inactive, it means the firewall isn’t running. Try starting it manually:
sudo ufw enable
If that fails, move on to the next steps.
2. Restart the UFW Service
Sometimes the issue is just a stuck service. Restart UFW and check its status again:
sudo systemctl restart ufw
sudo systemctl status ufw
If you see an error such as “failed to start Uncomplicated firewall”, continue troubleshooting.
3. Enable UFW at Boot
Make sure UFW is enabled to start automatically when the system boots:
sudo systemctl enable ufw
Then reboot your system to verify that it starts correctly:
sudo reboot
4. Check for Conflicting Firewall Services
Other firewall services like firewalld or custom iptables rules can interfere with UFW. Disable or remove them:
sudo systemctl stop firewalld
sudo systemctl disable firewalld
Then restart UFW again:
sudo ufw enable
5. Fix Broken or Missing UFW Rules
If the UFW configuration files are corrupted, reset them:
sudo ufw reset
sudo ufw enable
This resets all rules but may resolve startup issues caused by invalid configurations.
6. Check Logs for More Information
If UFW still won’t start, check the system logs for error details:
sudo journalctl -xe | grep ufw
Look for missing dependencies, permission errors, or conflicts with other services.
7. Reinstall UFW (Last Resort)
If none of the above steps work, reinstall UFW completely:
sudo apt remove --purge ufw -y
sudo apt install ufw -y
sudo ufw enable
This ensures a clean configuration and fresh dependencies.
Conclusion
When UFW fails to start, the issue is usually due to conflicting services, corrupted rules, or misconfigured startup settings. Following the above steps will help you restore your Linux firewall and secure your system again quickly.
How to Fix Firewall (UFW) Not Starting on Linux (F.A.Q)
Why does UFW fail to start automatically?
It might not be enabled at boot or is conflicting with another firewall service.
How do I know if UFW is running?
Use sudo ufw status verbose to check if it’s active and enforcing rules.
Can UFW and firewalld run together?
No. They manage the same underlying iptables, which can cause conflicts.
Does resetting UFW delete all rules?
Yes. sudo ufw reset clears all firewall rules and starts fresh.
