I have Oracle VM VirtualBox 5.1.38 installed for long time:

$ apt-cache policy virtualbox-5.1 

virtualbox-5.1:

  Installed: 5.1.38-122592~Ubuntu~xenial

  Candidate: 5.1.38-122592~Ubuntu~xenial

  Version table:

 *** 5.1.38-122592~Ubuntu~xenial 500

        500 http://download.virtualbox.org/virtualbox/debian xenial/contrib amd64 Packages

        100 /var/lib/dpkg/status

I have not ran kernel updates, or something DKMS-related today.

The problem started with "Implementation of the USB 2.0 controller not found!" as in this Q&A.

So I downloaded corresponding version of Oracle VM VirtualBox Extension Pack and tried to install it by clicking on the file in ~/Downloads folder.

Then VirtualBox opened, suggested me to install extpack:

I clicked Install and accepted license.

Then the following error window was shown:

The installer failed with exit code 127: Error creating textual authentication agent: Error opening current controlling terminal for the process (`/dev/tty'): No such device or address.

Same with console way of installation:

$ VBoxManage extpack install ~/Downloads/Oracle_VM_VirtualBox_Extension_Pack-5.1.38.vbox-extpack 

VirtualBox Extension Pack Personal Use and Evaluation License (PUEL)

...

Do you agree to these license terms and conditions (y/n)? y



License accepted. For batch installaltion add

--accept-license=b674970f720eb020ad18926a9268607089cc1703908696d24a04aa870f34c8e8

to the VBoxManage command line.



0%...

Progress state: NS_ERROR_FAILURE

VBoxManage: error: Failed to install "/home/norbert/Downloads/Oracle_VM_VirtualBox_Extension_Pack-5.1.38.vbox-extpack"

VBoxManage: error: The installer failed with exit code 127: Error creating textual authentication agent: Error opening current controlling terminal for the process (`/dev/tty'): No such device or address

VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component ExtPackManagerWrap, interface IExtPackManager

VBoxManage: error: Context: "RTEXITCODE handleExtPack(HandlerArg*)" at line 1201 of file VBoxManageMisc.cpp

My user is a member of vboxusers group.

What to do with this?

Virtualbox Extension Pack needs to be installed using root powers according to these bug reports:

• Extpack "Error creating textual authentication agent"


• ExtPack installation failure


• Extpack installation fails

Stack Exchange has the latest installation instructions

LatestVirtualBoxVersion=$(wget -qO - http://download.virtualbox.org/virtualbox/LATEST.TXT) && wget "http://download.virtualbox.org/virtualbox/${LatestVirtualBoxVersion}/Oracle_VM_VirtualBox_Extension_Pack-${LatestVirtualBoxVersion}.vbox-extpack"

https://www.virtualbox.org/download/hashes/${LatestVirtualBoxVersion}/SHA256SUMS

sudo VBoxManage extpack install --replace Oracle_VM_VirtualBox_Extension_Pack-${LatestVirtualBoxVersion}.vbox-extpack

VBoxManage list extpacks

Any of the following methods will solve the issue:

* GUI way

1. 
   

   Run VirtualBox as root

   
   
   

   sudo virtualbox
   
   

   
   



2. Go to File→Preferences (or Ctrl+G)



3. Open Extensions tab


4. Click top right button labeled with Add new package.


5. Select downloaded extpack, click Install, agree with license


6. Close VirtualBox

Then open VirtualBox as normal user and repeat steps 2-5 again.

* Terminal way

Install with VBoxManage command:

$ sudo VBoxManage extpack install 

~/Downloads/Oracle_VM_VirtualBox_Extension_Pack-5.1.38.vbox-extpack 

...

Successfully installed "Oracle VM VirtualBox Extension Pack".

As the result it is shown in Preferences→Extensions:

and in terminal:

$ vboxmanage list extpacks

Extension Packs: 1

Pack no. 0:   Oracle VM VirtualBox Extension Pack

Version:      5.1.38

Revision:     122592

Edition:      

Description:  USB 2.0 and USB 3.0 Host Controller, Host Webcam, VirtualBox RDP, PXE ROM, Disk Encryption, NVMe.

VRDE Module:  VBoxVRDP

Usable:       true 

Why unusable: