Troubleshooting

  • Using sha256sum command for ensuring file integrity

    1.0 SHA-2

    A cryptographic hash function (CHF) is an algorithm to map arbitrary size data, called the message, to a fixed sized bit array, called the hash value, or message digest. It is a one way function. It is not feasible to generate the original message from the hash value. A small change in the message ...

  • VirtualBox – Not able to access guest from the host OS

    Solution to the problem of not being able to access the guest OS from the host in VirtualBox is given with steps.

  • VirtualBox – unable to mount Guest Additions ISO file in virtual machine

    Solution to the problen of not able to mount VirtualBox Guest Additions CD image and installation of Guest Additions.

  • VirtualBox – vboxdrv kernel module is not loaded

    Resoution of the problem of “vboxdrv kernel module is not loaded” during the first time running of VirtualBox after installation.

  • VirtualBox – No Bootable medium found. System halted.

    Resolution of the error observed while running VirtualBox the first time, “No Bootable medium found. System halted”.

  • Simple Screen Recorder records only a black screen

    1.0 Problem

    Simple Screen Recorder program records only a blank black screen on Ubuntu Linux.

    2.0 Solution

    The problem is solved with the following steps.

    1. Close all programs.
    2. Log out.
    3. Start a fresh login procedure. Click on the user name.
    4. Before entering the password, find the gear icon in the bottom right corner of the screen. Clicking this icon gives two options, ...
  • Audacity: The cursor is not moving over the waveform during playback

    1.0 Problem

    The cursor does not move over the waveform during playback. It does not update during playback.

    2.0 Solution

    The problem was resolved with the following steps.

    1. Close any open Audacity session.
    2. Go to the /usr/share/applications directory.
    3. Open the file, audacity.desktop, in an editor.
    4. Find the line,
      Exec=audacity %F

      Replace it with, ...

  • Chromecast not connecting to Wifi

    1.0 Problem

    A change of Wifi network necessitated that the same be changed for a working chromecast device. When the chromecast was reconfigured using the Google Home app, it would not communicate with the new Wifi network. An error message was printed and the configuration session would end.

    2.0 Solution

    The problem was solved by doing a hardware ...

  • Gimp: How to stack the main window over the toolbox and layer windows

    When Gimp is installed fresh, the toolbox and layers windows are stacked on top of the main window and it is not possible to get the main window on the top. This can be quite annoying since one works mostly on the main window and the other two are required only ...

  • Everything is too small on desktop at 1080p

    After installing Ubuntu Linux on a laptop with screen resolution 1920×1080 pixels or more, you may find that the icons and text appear to be small. You can alleviate the problem by taking the following steps.

    1. Install gnome-tweak-tool

    $ sudo add-apt-repository universe
    $ sudo apt-get install gnome-tweak-tool
    

    2. Run gnome-tweak-tool

    1. Click on “Show Applications” to sell all applications. ...
  • Wacom tablet not connecting with Ubuntu Linux

    1.0 Error

    Wacom tablet connected to a laptop
    Wacom tablet connected to a laptop

    Wacom One CTL-672/KO-CX tablet was not connecting with a laptop running Ubuntu Linux 18.04 LTS. It was working fine ...

  • Connecting Wacom One CTL-672/KO-CX tablet to Ubuntu Linux

    Wacom One CTL-672/KO-CX is an 8.5 inch x 5.3 inch graphic tablet which can be connected to a computer via a USB port. The tablet comes with a pressure sensitive cordless ...

  • nginx 502 Bad Gateway

    1.0 502 Bad Gateway

    After the update of Linux on the web server, the website would not open in the browser. Instead the following error was displayed.

    502 Bad Gateway
    nginx/1.14.0
    

    2.0 Solution

    First we check the nginx server.

    $ ...
  • MCE hardware error cpu 0

    1.0 Error

    While running Ubuntu 18.04.1 on a laptop, the following errors were observed.

    mce: hardware error cpu 0 machine check 0 bank 6 ae0000000040110a
    mce: hardware error tsc 0 addr ffb07540 misc 238a0000086
    mce: hardware error processor 0:40651 time 1540082330 socket 0 Apic 0 microcode 24
    ipmi dmi invalid offset 0
    

    The system would stop in ...

  • Failed to fetch webpage, temporary failure resolving domain

    1.0 Error

    While configuring a Linux server, the error Failed to fetch webpage, temporary failure resolving domain was observed.

    $ sudo apt-get update
    Err:1 ... bionic InRelease
      Temporary failure resolving ...
    Err:2 ... bionic-updates InRelease
      Temporary failure resolving ...
    ...
    Reading package lists... Done
    W: Failed to fetch ...  Temporary failure resolving ...
    ...
    

    Also, the

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