Solutions for 17 bugs in Ubuntu 16.04 and Linux Mint 18


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No operating system is flawless. Ubuntu and Linux Mint are no exceptions.

Here you'll find solutions for some bugs in Ubuntu 16.04 and Linux Mint 18 (or in the applications that are part of a default installation of Ubuntu and Linux Mint).

Can't boot from install DVD: processor without PAE support

1. Does your computer have an old processor without PAE support? For many non-PAE processors from the Intel Pentium M series and Intel Celeron M series, PAE support can be forced. Which makes them fit for Linux Mint 18 after all.

You can force PAE upon such a processor by selecting Start with PAE forced in the boot menu from the Mint DVD. You can make that boot menu visible by interrupting the automatic boot, by hitting the space bar during the countdown.

Computer won't boot after installation of Ubuntu or Mint

2. Some computers, after a seemingly flawless installation of Ubuntu or Mint, won't boot. I'll describe two situations here.


a. You see the following error, in white letters on a black screen:

error: unknown filesystem
grub rescue>

In that case you've probably used an USB memory stick for the installation (Live USB). It happens sometimes, that the memory stick identifies itself as sda and the hard disk as sdb. And that's how it configures bootloader Grub then, during the installation!

After the installation bootloader Grub wants to boot from sdb, but sdb has disappeared: the hard disk should be addressed as sda now. The installer has therefore correctly installed and configured everything for sda, except for.... Grub.

In that case it suffices to redirect Grub to sda, which you can do as follows. The easiest method is when you use an Ubuntu or Mint DVD for that, because then you can be sure that there will be no new switching of sda into sdb in the live session.

When you don't have the option to use a DVD, then you might try a Live USB of Xubuntu 16.04 LTS, because that one probably has no switching problem (at least in my limited experience).


b. In another situation you may see one of these two errors, in white letters on a black screen:

error: invalid arch independent ELF magic.
grub rescue>

Or this error:

error: file '/boot/grub/i386-pc/normal.mod' not found.
grub rescue>


In that case the cause may be, that Ubuntu or Mint has installed a wrong kind of boot loader. Namely Grub for EFI / UEFI (grub-efi) instead of the ordinary Grub for BIOS.

Among others, this happens on a Lenovo B570e laptop. Although this computer has a UEFI and not a BIOS, this UEFI has been configured by Lenovo to behave as if it were a BIOS. That's why it needs the ordinary Grub for BIOS.

Reparation is then pretty simple: install the ordinary Grub with the Ubuntu or Mint DVD.

Computer boots straight into Windows 8.x or 10, after dual boot install

3. In certain cases, after an apparently successful installation of Ubuntu or Mint next to an existing Windows 8.x or 10, your computer might boot straight into Windows 8.x or 10. No boot menu then, in which to select Ubuntu or Mint.

This might be caused by a wrong boot priority order in the UEFI. If so, you can fix it like this (item 2.2, left column).

The installation of Ubuntu or Mint can't be finished: it fails halfway

4. Especially on older computers it could happen that the installation of Mint or Ubuntu, suddenly fails. This might be caused by the slideshow.

During the installation of Ubuntu and Mint you see a slideshow, with beautiful pictures about what to expect in your new Mint or Ubuntu. But sometimes this slideshow creates problems: the graphics card can't handle it, because the right driver hasn't been installed yet, and the installation stalls.

In that case you can remove the slideshow like this:

Launch a terminal.
(You can launch a terminal like this: *Click*)

Use copy/paste to transfer the following command line to the terminal:

sudo apt-get remove ubiquity-slideshow-*

Press Enter.

After the removal of the slideshow you can launch the installer again.

Swap use (swappiness) is too high: Ubuntu or Mint is too slow and uses the hard disk too much

5. This is especially noticeable on computers with relatively low RAM memory (2 GB or less): they tend to be far too slow in Linux Mint and Ubuntu, and Mint or Ubuntu accesses the hard disk too much. Luckily, this can be helped.

Note: does your computer have 4 GB RAM or more? Then you can skip this item, because with so much RAM you probably won't notice any benefits from applying it.

On the hard disk there's a separate partition for virtual memory, called the swap. When Ubuntu or Mint uses the swap too much, the computer slows down a lot.

Ubuntu's (or Mints) inclination to use the swap, is determined by a setting. The lower the setting, the longer it takes before Ubuntu or Mint starts using the swap. On a scale of 0-100, the default setting is 60. Which is much too high for normal desktop use, and only fit for servers.

A detailed explanation can be found here (link dead? Then download this pdf file with the same content).

Now the how-to:

a. Check your current swappiness setting:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (use copy/paste):

cat /proc/sys/vm/swappiness

Press Enter.

The result will probably be 60.

b. Make sure that you have installed the applications gksu and leafpad:

Type in the terminal (or copy/paste):

sudo apt-get install gksu leafpad

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

c. Then type in the terminal (use copy/paste):

gksudo leafpad /etc/sysctl.conf

Press Enter.

Scroll to the bottom of the text file and add your swappiness parameter to override the default, so copy/paste the following two green lines:

# Decrease swap usage to a more reasonable level
vm.swappiness=10

d. Save the text file and reboot your computer.

e. After the reboot, check the new swappiness setting:

Launch a terminal and type (use copy/paste):

cat /proc/sys/vm/swappiness

Press Enter.

Now it should be 10.

Note: if your hard disk is an SSD, your machine will benefit from an even bigger decrease in swappiness. That's because too many write actions, like frequent swapping, reduce the lifespan of an SSD. For an SSD I advise a swappiness of 1. Also check these tips for optimizing an SSD for your Linux.

The screen resolution is not right, after installation of the restricted proprietary driver for some NVIDIA graphics cards

6. Note: the following applies only to Nvidia graphics cards running on the Nvidia restricted driver.

a. First make sure that you have installed the applications gksu and nvidia-settings:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (or copy/paste):

sudo apt-get install gksu nvidia-settings

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

b. Then type in the terminal (use copy/paste):

gksudo nvidia-settings

Press Enter.

Now you can configure your screens properly, with this handy tool from Nvidia. As follows:

- Click on "X Server Display Configuration" (in the upper left)

- On the right: click on the tab Display (probably open already)

- Resolution:click on the arrow after "Auto"

- Choose the screen resolution that you want

- Click on "Save to X Configuration File"

- Click on "Save and exit"

- Do a full reboot of your computer. Now the screen resolution should be right.

The tools for updating or installing software malfunction

7. It can happen that the tools for updating or installing software (Update Manager, Software Manager, Software Updater or Software) malfunction, although you do have internet connection. The cause is usually a problem with the software lists.

In that case, you often see an error report with (among other things) this text:
E: encountered a section with no package: header
E: problem with Mergelist/var/lib/apt/lists


To repair this you can do the following.

Linux Mint: in Linux Mint you can solve this very easily: from the menu, launch Software Sources. Then click on the button Maintenance and then on the button Fix MergeList problems.

Ubuntu: in Ubuntu you have to do this:

a. First remove the old lists:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (use copy/paste):

sudo rm /var/lib/apt/lists/* -vf

Press Enter. Type your password when prompted; this remains entirely invisible, not even dots will show, this is normal. Press Enter again.

b. Now retrieve the new lists from the internet:

In the terminal (use copy/paste):

sudo apt-get update

Press Enter.

The problem should be over now.

Reboot fails

8. Some laptops won't reboot. The computer simply "hangs" after a rebooting attempt.

In most cases this has to do with BIOS and (U)EFI. You can remedy it as follows:

a. First make sure that you have installed the applications gksu and leafpad:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (or copy/paste):

sudo apt-get install gksu leafpad

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

b. Then type in the terminal (use copy/paste):

gksudo leafpad /etc/default/grub

Find the line:
GRUB_CMDLINE_LINUX=""

...and replace it by this line:
GRUB_CMDLINE_LINUX="reboot=efi"

Save the changes and close the file.

c. Now issue this command in the terminal (use copy/paste):

sudo update-grub

Press Enter. Type your password when prompted; your password will remain entirely invisible, not even dots will show, this is normal.

Now shut your computer down (no reboot!). Turn it on again, and after logging into your user account, try to reboot it. This should work now.

Hibernate and suspend don't always work well: they make some computers malfunction or even enter a coma

9. "Hibernate" and "suspend" still cause problems on some hardware, and unfortunately.... for much hardware there is no solution yet, because most manufacturers of BIOS and UEFI don't stick to the standards for implementing power saving.

Therefore it's better to turn off one or both of these sleep modes, if they don't work well on your computer.

"Hibernate" (suspend-to-disk) is the most agressive of the two sleep modes, which is why it causes problems more often than "suspend" (suspend-to-ram). If "suspend" does work well on your machine, you don't have to disable it, of course.

In Ubuntu, "hibernate" is therefore disabled by default, but "suspend" is enabled by default. Which I think is a reasonable compromise.

In Linux Mint however, unfortunately both "hibernate" and "suspend" are enabled by default. To be on the safe side, I advise to disable "hibernate" in Linux Mint in all cases. You can do that as follows:

Disable hibernation (suspend-to-disk, only necessary in Linux Mint)

9.1. You can disable hibernation (suspend-to-disk) like this:

a. Launch a terminal window.
(You can launch a terminal window like this: *Click*)

b. Copy the following command line and paste it into the terminal, in order to avoid typing errors (this is one line):

sudo mv -v /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla /

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

With that, you've moved the settings file that enables hibernation, to the main directory / (root). Thus rendering it ineffective. The new location is a safe storage, from which you can retrieve it again, should you ever wish to restore hibernation.

c. Reboot your computer. Hibernation should now no longer be one of the options in the shutdown menu.

(with thanks to riffbiker from the Linux Mint forum)

d. On a laptop, it's advisable to check the power manager settings: you'll have to find alternatives for hibernation.

e. The troublesome hibernation shouldn't be enabled by default at all... So please help to improve Linux Mint, by supporting this idea of mine:
http://community.linuxmint.com/idea/view/5482

How to undo

9.1.1. Do you want hibernation back? The above hack is easily reversible. Undoing it is very simple:

a. Launch a terminal window.
(You can launch a terminal window like this: *Click*)

b. Copy/paste the following line into the terminal (it's one line):

sudo mv -v /com.ubuntu.enable-hibernate.pkla /etc/polkit-1/localauthority/50-local.d

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

Reboot your computer. The hibernate option should be back now.

(continued in the column on the right)

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Disable suspend (suspend-to-ram)

9.2. You can disable suspend (suspend-to ram) as follows (only do it when really necessary, because it's generally a useful feature):

a. First make sure that you have installed the applications gksu and leafpad:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (or copy/paste):

sudo apt-get install gksu leafpad

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

Leave the terminal window open for the actual hack.

b. Copy/paste the following line into the terminal (use copy/paste to prevent typo's, it's one line!):

sudo touch /etc/polkit-1/localauthority/90-mandatory.d/disable-suspend.pkla

Press Enter.

c. Copy/paste the following line into the terminal (use copy/paste to prevent typo's, it's one line!):

gksudo leafpad /etc/polkit-1/localauthority/90-mandatory.d/disable-suspend.pkla

Press Enter.

d. Copy and paste the following green text into that empty text file:
[Disable suspend (upower)]
Identity=unix-user:*
Action=org.freedesktop.upower.suspend
ResultActive=no
ResultInactive=no
ResultAny=no

[Disable suspend (logind)]
Identity=unix-user:*
Action=org.freedesktop.login1.suspend
ResultActive=no

[Disable suspend for all sessions (logind)]
Identity=unix-user:*
Action=org.freedesktop.login1.suspend-multiple-sessions
ResultActive=no
Save the text file and close the text editor.

e. Reboot your computer (full reboot). Suspend should now no longer be one of the options in the shutdown menu.

f. On a laptop, it's advisable to check the power manager settings: you'll have to find alternatives for suspend, for actions like closing the laptop lid.

How to undo

9.2.1. Do you want suspend back? The above hack is easily reversible. Undoing it is very simple:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Copy/paste the following line into the terminal (it's one line):

sudo rm -v /etc/polkit-1/localauthority/90-mandatory.d/disable-suspend.pkla

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

Reboot your computer. The suspend option should be back now.

Some laptops: hard disk constantly clicks and spins up and down

10. Some laptop hard disks have a serious problem: they keep constantly clicking and spinning up and down. Not all laptop hard disks have this problem: it depends on the brand and model.

The cause is the firmware of the disk: its power management feature has been implemented far too agressively by the manufacturer. This is very unhealthy for the disk and may shorten its lifespan considerably.

Some operating systems contain a built-in correction for this firmware error, but many types of Linux don't.

The solution is not too difficult:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (use copy/paste):

sudo hdparm -B 254 /dev/sda

Press Enter. Type your password when prompted; this remains entirely invisible, not even dots will show, this is normal. Press Enter again.

Now the nasty clicks should stop.

With this command you don't entirely disable the power management of the disk, but you limit it to a minimum. Positive side effect: your laptop becomes a little faster.

The "price" you pay is a somewhat higher power consumption, and therefore a slightly decreased battery time. But not much.

The command is for the current session only. If you want to make it permanent, you can do this:

a. First make sure that you have installed the applications gksu and leafpad:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (or copy/paste):

sudo apt-get install gksu leafpad

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

b. Then type in the terminal (use copy/paste):

gksudo leafpad /etc/hdparm.conf

Press Enter.

Now text editor Leafpad opens a text file. Add the following text, at the very end of the text (use copy paste to avoid errors):
/dev/sda {
    apm = 254
    apm_battery = 254
}
c. Save the file, close Leafpad and reboot your computer (full reboot).

d. Finally, disable hibernate and suspend, because the hard disk will start clicking again after waking up from those (see item 8 on this page).

This is actually no fault of Ubuntu or Mint, but of the hard disk manufacturer, who provides bad firmware.... It's not good when an operating system has to correct a firmware fault.

Wireless internet is sometimes being blocked by Bluetooth

11. On some laptops, wireless internet (wifi or 3G) is being blocked by Bluetooth. In that case, the solution is simple: temporarily disable Bluetooth, by clicking on the bluetooth icon in the upper panel. Then reboot your laptop. Bluetooth should remain disabled and you should be able to make wifi or 3G connection.

If Bluetooth should be enabled again after reboot, disable it more thouroughly by disabling it in the BIOS of your laptop.

Large PDF documents can't be printed entirely

12. The default PDF reader in Ubuntu is Document Viewer (Evince). Evince sometimes has difficulty handling large PDF documents, which may cause printing failure.

To work around this problem, you can use a lightweight alternative PDF reader called xpdf. Unlike Evince, xpdf has no difficulty printing large PDF documents.

You can install xpdf with a few mouseclicks in the application Software (Ubuntu) or Mints Software Manager, because it's present in the default software repositories of Ubuntu and Mint.

Adobe Flash Player: wrong colours (blue, pink or purple) or browser crash

13. Not a fault of Ubuntu or Mint, but rather annoying: on some computers, when you view video's in Adobe Flash Player, the video colors are wrong: it's all blue, purple or pink. Also Firefox may crash when viewing Flash content.

The cause is the hardware acceleration in Adobe Flash Player for Linux: this malfunctions on certain video cards.

Thankfully, there's a simple workaround that's effective: disable the hardware acceleration in Adobe Flash Player.

Note: for this workaround it's best to temporarily disable the visual effects (not necessary for Xubuntu and Lubuntu).

- surf to the website Flash Player Help (or to another website with a certain kind of Flash content; not Youtube, because it has a different kind)

- wait until the content of the website has been loaded

- right-click mouse on the tree animation - Settings... - remove the tick for:
Enable hardware acceleration

See the screenshot below (click on it to enlarge it):

https://sites.google.com/site/easylinuxtipsproject/bugs/Screenshot-FP1.png?attredirects=0

Click the "Close" button.

Can't install Adobe Flash Player

14. Installing Adobe Flash Player is usually easy. But on some old computers this doesn't work, because the CPU doesn't support sse2. That support is required for the latest versions of Flash Player for Linux.

This is how you can check whether your CPU supports sse2:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (use copy/paste):

cat /proc/cpuinfo | grep sse2

Press Enter.

In the output you should find sse2 in red text. If you don't get any output at all, then unfortunately you can't use Flash Player on that machine.

A partial workaround is, to let Youtube show its content by means of html5 instead of flash: http://www.youtube.com/html5

Note: some how-to's advise in such a case, to install an older version of Flash Player, that doesn't require sse2 support. Don't do that!

Adobe Flash Player is one of the most heavily attacked applications around. Much malicious software on websites, targets Flash Player. So it's absolutely unsafe to use such an older version, also in Linux.

The size of the log files in /var/log gets out of hand

15. Thankfully it's a rare problem, but anyway: some errors create huge log files, causing rapid loss of disk space. When you have this problem, you should of course fix the underlying error(s) as soon as possible.

In order to read the gigantic log files you'd better not use a normal text editor, because it can be bogged down by the sheer size of the file. Use a terminal command instead:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (use copy/paste):

tail -100 /path-to-logfile/logfile > disk_eater.log

Press Enter. That way you've created a small text file, called disk_eater.log, which contains the last 100 lines in the log file. It's in your personal folder. You can simply double-cick it to read its contents. This should enable you to find the culprit.

Example for the log file syslog:
tail -100 /var/log/syslog > disk_eater.log

As a temporary emergency measure you can also limit the size of the log files, which you can do as follows:

a. First make a backup copy of your current log settings, in the following way:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (use copy/paste):

sudo cp -v /etc/logrotate.d/rsyslog /rsyslogbackup

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

b. Then make sure that you have installed the applications gksu and leafpad:

Type in the terminal (or copy/paste):

sudo apt-get install gksu leafpad

Press Enter and submit your password. Please note that the password will remain invisible, not even asterisks will show, which is normal.

c. Then type in the terminal (use copy/paste):

gksudo leafpad /etc/logrotate.d/rsyslog

press Enter.

d. Delete the entire content of that text file and replace it by the green text below (use copy/paste):
/var/log/syslog
{
      rotate 1
      maxsize 10M
      hourly
      missingok
      notifempty
      delaycompress
      compress
      postrotate
           reload rsyslog >/dev/null 2>&1 || true
      endscript
}

/var/log/mail.info
/var/log/mail.warn
/var/log/mail.err
/var/log/mail.log
/var/log/daemon.log
/var/log/kern.log
/var/log/auth.log
/var/log/user.log
/var/log/lpr.log
/var/log/cron.log
/var/log/debug
/var/log/messages
{
      rotate 1
      maxsize 10M
      hourly
      missingok
      notifempty
      compress
      delaycompress
      sharedscripts
      postrotate
           reload rsyslog >/dev/null 2>&1 || true
      endscript
}
e. Save the modified text file and close it. This limits the size of each log to 10 megabytes, and the number of old copies to 1. Logrotate will now be executed every hour.

f. Reboot your computer.

Has the underlying problem been solved? Then simply delete /etc/logrotate.d/rsyslog, rename /rsyslogbackup to /rsyslog and move it to the folder /etc/logrotate.d.

Booting takes a very long time

16. On some hardware, booting lasts extremely long. You can try to find the cause of a slow boot as follows:

Launch a terminal window.
(You can launch a terminal window like this: *Click*)

Type (copy/paste to avoid errors):

systemd-analyze blame

Press Enter.

Sometimes the Network Time Protocol (NTP) is the culprit. If it's ntp.service that's eating all that time, you might try this:

Type (copy/paste to avoid errors):

sudo systemctl disable ntp

Press Enter. Type your password when required; this remains entirely invisible, not even dots will show, this is normal.

The price you pay for disabling NTP, by the way, is that your system time is no longer being synchronized with NTP servers. This is usually only a minor inconvenience.

Do you want to undo this? That's easy:

sudo systemctl enable ntp

Weak graphics card: disable the hardware acceleration in Firefox, Chrome and Chromium

17. Some older or weaker video cards have trouble because of the hardware acceleration that's on by default in Firefox, Chrome and Chromium. When you experience graphics problems in those web browsers (delay when typing text, problems with displaying video's), disable it as follows:

Firefox:
Click on the button with three horizontal dashes in the top right corner - Preferences - Advanced:
remove the tick for: Use hardware acceleration when available.
Close Firefox and launch it again.

Chrome / Chromium:
Click on the button with three horizontal dashes in the top right corner - Settings - Show advanced settings...
section System: remove the tick for: Use hardware acceleration when available.
Close Chrome / Chromium and launch it again.

Official bug lists for Linux Mint and Ubuntu

18. Have a look at the official bug lists for Linux Mint, Ubuntu, Xubuntu and Lubuntu (look for the header "Known issues" or "Known problems"):

Bug list for Linux Mint 18 Cinnamon

Bug list for Linux Mint 18 Mate

Bug list for Linux Mint 18 Xfce

Bug list for Ubuntu 16.04

Bug list for Xubuntu 16.04

Bug list for Lubuntu 16.04


Want more tips?

Do you want more tips and tweaks for Ubuntu or Linux Mint? There's a lot more of them on this website!


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