Troubleshooting

  • 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 ...
  • 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

    5. 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 ...

    6. 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 ...

    7. Everything is too small on desktop at 1080p

      After installing Ubuntu Linux on a laptop with screen resolution 1920x1080 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 ...
    8. 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 ...

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

      Wacom CTL-672 connected to computer running 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 ...

    10. nginx 502 Bad Gateway

      1.0 502 Bad Gateway

      nginx 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.

      $ ...
    11. MCE hardware error cpu 0

      1.0 Error

      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 ...

    12. 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

    13. Composer Manager: Composer’s install command must be run

      1.0 Error

      After updating the Drupal 7 version in a website, the following error was observed in the configuration of the Composer Manager module.

      Composer Manager: Composer's install command must be run to generate the autoloader and install the required packages.
      

      The above message was followed by the status of packages managed by the Composer. ...

    14. Drupal: Notice: Trying to get property of non-object in block_block_view()

      1.0 Error

      After updating the website to a new version of Drupal 7, the following error was printed on the web pages.

      Notice: Trying to get property of non-object in block_block_view() (line 247 of modules/block/block.module).
      

      2.0 Resolution

      The error was resolved by the following steps.

      2.1 Turn off block caching

      From the Administration menu, Select Configuration --> ...

    15. Dovecot: Fatal: Error in configuration file /etc/dovecot/dovecot.conf: protocols: Unknown protocol: sieve

      1.0 Error:

      While configuring the Dovecot Mail Delivery Agent, the Dovecot server would not start and the following error messages were printed.

      $ sudo systemctl start dovecot
      Job for dovecot.service failed because the control process exited with error code. See "systemctl status dovecot.service" and "journalctl -xe" for details.
      $ systemctl status dovecot.service
      ● dovecot.service - Dovecot IMAP/POP3 ...
    16. How to execute PHP code in HTML under nginx server

      1.0 Error

      PHP code was not getting executed in the index.html file when the concerned website was opened in a browser. nginx server was being used to serve the web pages.

      2.0 Solution

      2.1 Install php7.0-fpm

      $ sudo apt-get install php7.0-fpm
      
      2.2
    17. SSL Certificate expired, site not opening

      1.0 ERROR

      A website stopped opening in browser, giving the error that the SSL certificate was either invalid or had expired.

      2. SOLUTION

      Checking the website with wget,

       $ wget https://www.example.com
      --2018-01-14 16:58:36--  https://www.example.com/
      Resolving www.example.com (www.example.com)... 198.51.100.12, 2001:db8:1221:2341:f03c:f27b:12fa:2123
      Connecting to www.example.com (www.example.com)|198.51.100.12|:443... connected.ERROR: cannot verify www.example.com's certificate, issued by ‘CN=Typical Encryption Authority X3,O=Typical Encryption,C=XX’:
       ...