Troubleshooting frequent problems

Could not access KVM kernel module:

The system shows this message on trying to start a virtual Machine:

Could not access KVM kernel module: Permission denied failed to initialize KVM: Permission denied

That means the host has no virtual capabilities or are disabled. Try running:

sudo tail -f /var/log/syslog
sudo modprobe kvm-intel

If it shows a message like this it means the BIOS Virt feature must be enabled:

kvm: disabled by bios

or try: kvm-ok command

INFO: /dev/kvm does not exist
HINT:   sudo modprobe kvm_intel
INFO: Your CPU supports KVM extensions
INFO: KVM (vmx) is disabled by your BIOS
HINT: Enter your BIOS setup and enable Virtualization Technology (VT),
  and then hard poweroff/poweron your system
KVM acceleration can NOT be used

Dealing with permissions

The system may deny access to some directories.

On Screnshots ( requires review )

That problem showed up in Vanilla Linux 4.10.

When running the screenshot command it returns:

failed to open file '/var/cache/libvirt/qemu/qemu.screendump.31DvW9': Permission denied


At the file : /etc/apparmor.d/usr.lib.libvirt.virt-aa-helper

/var/cache/libvirt/qemu/ rw,
/var/cache/libvirt/qemu/** rw,

Error with MySQL version < 5.6

For example the following message:

DBD::mysql::db do failed: Invalid default value for 'date_send' at /usr/share/perl5/ line 276.

DEFAULT CURRENT_TIMESTAMP support for a DATETIME (datatype) was added in MySQL 5.6.

Upgrade your MySQL server or change: datetime for timestamp

date_send datetime default now(),

More information about.

MySQL binlogs fill the disk

If you are using MySQL it may create a lot of binlog files that in some cases may fill your disk drive. If you are not using replication it is safe to disable them if it is only used for Ravada.

Edit the file /etc/mysql/mysql.conf.d/mysqld.cnf comment the binlog lines and add skip-log-bin=true :


skip-log-bin = true
# binlog_expire_logs_seconds        = 2592000
# max_binlog_size   = 100M

To purge the logs run the mysql client and type:

mysql> purge binary logs before '2024-11-15';

Spice-Warning Error in certificate chain verification

(/usr/bin/remote-viewer:2657): Spice-Warning **: ssl_verify.c:429:openssl_verify: Error in certificate chain verification: self signed certificate in certificate chain (num=19:depth1:/C=IL/L=Raanana/O=Red Hat/CN=my CA)

spicec looks for %APPDATA%spicecspice_truststore.pem / $HOME/.spicec/spice_truststore.pem. This needs to be identical to the ca-cert.pem on the server, i.e. the ca used to sign the server certificate. The client will use this to authenticate the server.

Network is already in use

If running VMs crash with that message:

libvirt error code: 1, message: internal error: Network is already in use by interface

You are probably running Ravada inside a virtual machine or you are using the private network that KVM uses for another interface. This is likely to happen when running Ravad in a Nested Virtual environment.

Solution: Change the KVM network definition. Edit the file /etc/libvirt/qemu/networks/default.xml and replace all the

192.168.122 network instances by another one, ie: 192.168.123.

sudo virsh net-edit default
<ip address='' netmask=''>
     <range start='' end=''/>

Then reboot the whole system.

Copy & paste integration does not work

Make sure that the VM has a Spice communication channel (com.redhat.spice.0) and that the guest additions have been installed.

The Spice channel can be added through virt-manager’s Add Hardware wizard or editing the XML:

<channel type='spicevmc'>
  <target type='virtio' name='com.redhat.spice.0'/>
  <address type='virtio-serial' controller='0' bus='0' port='1'/>

Linux guests must install the spice-vdagent package, while Windows guests require this installer (source)

Resizing the viewer window does not change the guest display resolution

This feature requires the Spice communication channel and the guest additions. See above for instructions.

Windows 10 perfomance issues

thanks to @rlunardo

Problems with the time of the VM guest

You create a VM and you set the time correctly. After this VM becomes base and the time appears altered (-2h, +2h,…)

This is due to the parameter:

<clock offset='utc'>  vs    <clock offset='localtime'>

You can modify XML file from the command:

virsh edit <machine_name>

Content is empty after upgrade

If after upgrade you get an almost blank screen it is probably a matter of cached javascript or CSS. Type SHIFT+F5 or SHIFT+Reload button in your browser. You could also clean browser history so it gets refreshed the next time you access the Ravada frontend.

Error: Web Service connection failed

If you get this error on the frontend, carefully review this documentation :

It is very common to miss some step, so please take your time and restart all the services afterwards.

Virtual machines won’t complete the shutdown

This may happen in some upgrades to Ubuntu 20.04. Virtual machines appear in the state in shutdown and won’t complete the shutdown process.

You may notice if you type virsh list:

# virsh list
 Id   Name       State
2    tst20-04   in shutdown

The solution is to change the apparmor settings. Edit the file /etc/apparmor.d/usr.sbin.libvirtd below:

# For communication/control from libvirtd
signal (receive) peer=libvirtd,
signal (receive) peer=/usr/sbin/libvirtd

Reboot the server and the virtual machines shutdown will work again.

Thanks to Jim Fehlig from

internal error: cannot load AppArmor profile libvirt

Set security_driver = “none” in /etc/libvirt/qemu.conf

#       security_driver = [ "selinux", "apparmor" ]
#security_driver = "selinux"
security_driver = "none"

Then restart libvirt service

sudo systemctl restart libvirtd

Cloned Ubuntu Server VMs assigned same IP

When cloning a virtual machine with Ubuntu Server (possibly applicable to other distributions as well), it has been observed that the cloned machines are assigned the same machine ID in the /etc/machine-id file. As a result, the Netplan networking configuration attempts to resolve DHCP based on this ID instead of the MAC address, resulting in both machines being assigned the same IP address.

To resolve this issue, edit the file /etc/netplan/<configuration-file>.yaml adding the next lines in the proper interface:

Add the following lines to the network configuration for each cloned machine:

dhcp4: yes
dhcp-identifier: mac

Apply the updated Netplan configuration:

sudo netplan apply

With these steps, each cloned virtual machine will be assigned a unique IP address based on its MAC address, resolving the issue of both machines receiving the same IP.