After an unsuccessful installation of MX 21.0, I had to return to MX 19.4 and configure the system from scratch.

Why is the MX-19.4 "Patio Feo" better than the MX-21 "Wildflower" version?

1. The standard method of creating bootable media "dd if=file.iso of=/dev/sdd bs=1M" is not suitable for installing MX 21
   because with this option, the system does not boot from the USB drive (the cursor blinks on a black screen).
   You need to write an ISO file to a flash drive formatted in NTFS using the RuFus utility.
2. The installation of MX 21 only reached 94%, stopped when executing the command /bin/sync
3. MX 21 users have complained about very slow performance on older PCs (for which the MX-19 is better suited).

4. Since the installation program has been redesigned in MX 21, the choice of installing the bootloader is more complicated - MBR, PBR, ESP. As with the MX-19, the PBR clause needs an explanation. If the UEFI is in Legacy mode (UEFI BIOS, that is, the hard drive is partitioned with the MBR partition type), then when you select the MBR option and install it in the boot sector, if the installation program crashes or freezes, the computer will boot (it is impossible to boot both Linux and Windows), since GRUB is faulty. The treatment "destroys" the Linux boot and restores the Windows boot:

   • Boot from the Windows CD, go to the "Recovery Environment" and run the commands in it:

   bootrec /FixMbr
   
   bootrec /FixBoot
   
   bootrec /RebuildBCD

In my case I had to work extra hard:

bootrec /FixMbr
bcdedit /export C:\BCD_Backup
c:
cd boot
attrib bcd -s -h -r
ren c:\boot\bcd bcd.old
bootrec /FixBoot
bootrec /RebuildBCD

Note: if when executing the command boorec /FixBoot the error "Element not found" is displayed,
then you need to make the first Windows partition (“Reserved by the system”) active using diskpart:

diskpart
select disk 0
select partition 1
active
exit

Addition: if there is only one Windows partition on the hard drive (which is boot and system partition, instead of the EFI system partition), but the boot files on it are destroyed, the following method will help: * boot from the Windows 10 installation flash drive and enter the recovery console, where run the commands

cd /d c:\boot
bcdboot c:\Windows /L ru-ru /S c: /F ALL

Where /L is the language, /S is the forced indication of the C: drive instead of the EFI partition, /F ALL is the firmware type. Allowed values ​​are UEFI, BIOS, and ALL. Obviously, if there is an EFI partition, the /S c: parameter should not be specified.

Result:"Download files created successfully".

Steps after installing MX 19.4

1. Regional settings (“locale”)

1) Configured the locale (operating system settings for the national language and fonts):
I left only Russia and the USA, UTF-8 encoding.

program "Start" - "Settings" - "System Locales" can be called from the command line:

dpkg-reconfigure locales

2. Update

2) If the system is dual boot (Windows / Linux), then immediately after installing 19.4 there will be no “Windows” item in the Grub boot menu.
You need to run the "update-grub" command, which will scan the hard drives and detect installed operating systems (including Windows OS), and add them to the Grub2 boot menu:

sudo update-grub

3) Immediately updated the "Debian 10 Buster" packages over the Internet:

sudo apt-get update
sudo apt-get upgrade

At the same time, the installed intel-firmware package, amd-microcode and the display driver were updated.
About 300 MB of packages were installed. Installation took about 30-40 minutes.
Upon completion, I rebooted the PC to apply the changes.

4) Switched in the directory /etc/apt/sources.list.d repositories for version "Debian 11 Bullseye" with all updates.

sources.list:

deb http://deb.debian.org/debian bullseye main contrib non-free
deb-src http://deb.debian.org/debian bullseye main contrib non-free

deb http://deb.debian.org/debian-security/ bullseye-security main contrib non-free
deb-src http://deb.debian.org/debian-security/ bullseye-security main contrib non-free

deb http://deb.debian.org/debian bullseye-updates main contrib non-free
deb-src http://deb.debian.org/debian bullseye-updates main contrib non-free

deb http://deb.debian.org/debian bullseye-proposed-updates main contrib non-free
deb-src http://deb.debian.org/debian bullseye-proposed-updates main contrib non-free

deb http://deb.debian.org/debian bullseye-backports main contrib non-free
deb-src http://deb.debian.org/debian bullseye-backports main contrib non-free

deb http://deb.debian.org/debian bullseye-backports-sloppy main contrib non-free
deb-src http://deb.debian.org/debian bullseye-backports-sloppy main contrib non-free

testing.list:

deb http://mirror.truenetwork.ru/mxlinux/mx/repo/ buster main non-free
deb http://mirror.truenetwork.ru/mxlinux/mx/repo/ buster ahs
deb http://mirror.truenetwork.ru/mxlinux/mx/testrepo/ buster test

Installation of new versions of packages took more than 4 hours with stops for requests to update configuration files
Everywhere, except for setting up the package, grub-pc chose to replace .conf with new versions.

sudo apt-get update
sudo apt-get upgrade

In the window with the request during installation, in the GRUB settings, I checked the installation only on the /dev/sda device

After the update, the MX-19.4 operating system booted without problems - into the dual boot menu of both Linux and Windows.

lsb_release -a program messages indicate the release:

Distributor ID: Debian
Debian GNU/Linux 11 (bullseye).
Release: 11
Codename: bullseye

The only drawback is kernel 4.19.0-16-amd64, which is outdated.

5) This point is not necessary. Update from the bullseye-backports repository

Let's install kernel 5.10 and other newer ones from the Debian Backports repository (the purpose is clear from the translation of the words back and ports - adaptation of newer software for older OS versions).

sudo apt -t bullseye-backports upgrade

228 MB of archives were downloaded. The installation began and took 50 minutes.
It can be seen that the package manager has pulled up a new kernel 5.14.0.
When asked to update configuration files, the answer was positive everywhere - “Y”.

Now the kernel according to the command output uname -r the following:

5.14.0-0.bpo.2-amd64

The network via Wi-Fi works, everything is fine.

6)Update: next day completed package installation - command "apt dist-upgrade"- an intelligent system for installing the latest versions of software packages that are available from repositories specified through /etc/apt/sources.list.d/*.
Unlike simple apt upgrade, команда apt dist-upgrade removes and adds packages according to dependencies, in order to obtain the latest version of installed packages for a given distribution.

sudo apt dist-upgrade

Updating using the "dist-upgrade" command downloaded 500 MB of packages.

During the display of package installation information, messages appeared about the temporary removal of a small number of packages:

• python (because python2 is not needed, it has been replaced by python3 everywhere)
• python-minimal (from an old version of python, the package is deprecated, not available from sources.list)
• gimp-python (has unmet python2 dependencies)
• libgcc8-dev (package not found in the new version of the distribution from sources.list)
• libstdc++-8-dev (package not found in the new version of the distribution from sources.list)
• fuse (since replaced by fuse3)
• disk-manager (package not found in the new version of the distribution from sources.list)
• libreoffice-draw (reinstalled with new version during apt-get dist-upgrade)
• libreoffice-base (reinstalled with new version during apt-get dist-upgrade)
• libreoffice-impress (reinstalled with new version during apt-get dist-upgrade)
• libreoffice-writer (reinstalled with new version during apt-get dist-upgrade)
• libreoffice-common (reinstalled with new version during apt-get dist-upgrade)

ОднBut later, while executing the same command apt-get dist-upgrade, данные пакеты были установлены заново, точнее, переустановлены с новыми версиями. Например, для языка python 3 установлен пакет python 3.9.2-3. Таким образом, команда apt-get dist-upgrade affects the system more significantly.

The situation with the "disk-manager" package is unclear

• this package was not found in the Debian 11 "Bullseye" distribution. Apparently it was included in MX19 based on "Buster", but not included in newer OSs:
  https://packages.debian.org/search?keywords=disk-manager

There are no problems with other packages. For example, the compton 0.1.beta package was replaced by 1.1, flatpak from version 1.2.5 immediately to version 1.10.5, the synaptic package manager from version 0.90+mx19 to 0.90.2.

This update does not upgrade Debian 11, only package versions are changed.

7) Cleaning (removing unnecessary packages from the system)

sudo apt autoremove
sudo apt autoclean

8) Reboot and evaluate available resources.

sudo reboot

After the reboot, a window appeared with a message about replacing CliIt with Diodon:

"ClipIt has been deprecated and is no longer supported in Debian"
Diodon, a supported replacement for ClipIt, has been automatically installed for your convenience.
OK

The system is fully loaded, there are almost no errors. ;-)
"network manager is not running."

sudo service network-manager start

"network-manager": unrecognized service

!Solution: I independently found out that Network Manager, which manages network connections, works fine in SystemD service startup control mode.

To do this you need:

• or manually select the boot option (startup option) "...SystemD" from the Grub menu.
• or add to the kernel parameters in the file /etc/default/grub in the line GRUB_CMDLINE_LINUX_DEFAULT (затем выполнить команду sudo update-grub)
• or in the graphical application "MX boot options" configure and apply the kernel parameter: "Start" -> "Settings" -> "MX Tools" ->

  "MX Boot Options" -> "Kernel Options" ->
  quiet splash init=/lib/systemd/systemd

3. Screen

6) Setting the screen scale. Since the netbook screen resolution is only 1024x600 pixels, part of the user interface (lists, buttons at the bottom of the window) for many programs extends beyond the screen. Web pages may also appear too large. To fix this problem, you need to change the scale of display of information on the screen in the operating system:

Start - Settings - MX Tweak - Screen

xrandr scaling - 0.90

Apply - Close.

Comparison of real RAM consumption:

MX-19 kernel 5.14 - uses 475 MB,
MX-21 (Live USB) kernel 5.14 - uses 547 MB.

That is, the MX-21 OS consumes more RAM than the MX-19.

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