Virt-Manager network not working

I can’t get virt-manager to work. I followed the step on the wiki page to install. Also did sudo virsh net-autostart default. But still nothing. When I finish the configuration steps it doesn’t show my network,

and gives the below error.

The error

Unable to complete install: 'Requested operation is not valid: network 'default' is not active'

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/createvm.py", line 2001, in _do_async_install
    installer.start_install(guest, meter=meter)
  File "/usr/share/virt-manager/virtinst/install/installer.py", line 701, in start_install
    domain = self._create_guest(
  File "/usr/share/virt-manager/virtinst/install/installer.py", line 649, in _create_guest
    domain = self.conn.createXML(install_xml or final_xml, 0)
  File "/usr/lib/python3.9/site-packages/libvirt.py", line 4376, in createXML
    raise libvirtError('virDomainCreateXML() failed')
libvirt.libvirtError: Requested operation is not valid: network 'default' is not active

And that’s it, what should I do?

Open up wirt-manager and go to edit->connection details. Then select virtual networks and the select the default network and click the start network button. You will get an error. Let us know what that error is.

Yep, this.

Error starting network 'default': internal error: Failed to initialize a valid firewall backend

Traceback (most recent call last):
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 65, in cb_wrapper
    callback(asyncjob, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/asyncjob.py", line 101, in tmpcb
    callback(*args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/libvirtobject.py", line 57, in newfn
    ret = fn(self, *args, **kwargs)
  File "/usr/share/virt-manager/virtManager/object/network.py", line 69, in start
    self._backend.create()
  File "/usr/lib/python3.9/site-packages/libvirt.py", line 3446, in create
    raise libvirtError('virNetworkCreate() failed')
libvirt.libvirtError: internal error: Failed to initialize a valid firewall backend

EDIT: I found the below answer in SO.

Installing ebtables and dnsmasq seems to fix the problem. Don’t forget to restart the libvirtd service.

The commands:

sudo pacman -Syu ebtables dnsmasq
sudo systemctl restart libvirtd

Don’t know if it’s correct for this though.

Make sure you have the packages dnsmasq and either iptables-nft or ebtables installed. In most cases, iptables-nft is what you want.

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Working … Isn’t iptables-nft and dnsmasq needed part for the main virt-manager installe? is it situational?

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It is needed if you want a network in your VM but since that isn’t a hard requirement they are optional dependencies.

Ah ok. It would be grate if this would get mentioned in the WiKi. If this error happens install these and do this.

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