If the < a href=https://cleanersuite.com/avast-firewall-wont-start/> Avast firewall won't turn on in Windows 10 , try these things to resolve the issue. Make sure that your firewall is enabled and that all settings are configured properly. But sometimes restarting your system will also resolve this issue. Check the Windows firewall settings and reinstall Avast again. Check the other security software if any is enabled in the system.