Symptoms

When I start a virtual machine I get the following error:

    Unable to load the Parallels Driver

Cause

• Parallels Desktop kernel extensions were not allowed in macOS System Preferences
• macOS permissions issue
• Mac is running in Safe mode
• A possible influence of antivirus applications

Resolution

1. Restart your Mac.

2. If you're running macOS 10.13 or newer, open System Preferences > Security & Privacy > General > click Allow next to the corresponding message:

     3. Make sure the version of Parallels Desktop installed on your Mac is compatible with the version of OS X you are running. If it is not compatible, upgrade to the latest version of Parallels Desktop.

     4. Update Parallels Desktop to the latest build. In Mac menu click on Parallels Desktop > Check for Updates... Then download and install the update if one is available. If the problem persists, proceed to the next step.

     5. Try disabling available antivirus applications on your Mac because they might affect loading Parallels Desktop. Alternatively, you can add Parallels Desktop to the white list of the respective antivirus application(s).

     6. Uninstall Parallels Desktop using the instructions from KB124255. Once Parallels Desktop is uninstalled, reboot your Mac and install Parallels Desktop again.

     7. Make sure VT-x virtualization technology is enabled on your Mac: https://support.apple.com/en-us/HT203296 

     8. If your Mac is running in a Safe Mode, do the following:

• Open Finder > Applications > Utilities > Terminal application.

• Paste the following command into Terminal and press Return/Enter:

  sudo nvram boot-args=""
  

• Enter your Mac user account password when prompted, then press Return/Enter.

  NOTE: You will not see password characters as you type. It is normal Terminal behavior. Just type the password in and press Return/Enter.

• Restart Mac, and start your virtual machine.

For additional information please refer to support.apple.com/kb/HT1455