Posicionarse en el directorio /tmp

cd /tmp

Descargar el archivo de PHPMyAdmin del sitio de respositorios oficial

wget https://files.phpmyadmin.net/phpMyAdmin/5.1.1/phpMyAdmin-5.1.1-all-languages.zip

Instalar el unzip

apt install unzip

Descomprimir el archivo phpMyAdmin-5.1.1-all-languages.zip

unzip phpMyAdmin-5.1.1-all-languages.zip

Mover phpMyAdmin-5.1.1-all-languages.zip a /usr/share/phpmyadmin

mv phpMyAdmin-5.1.1-all-languages /usr/share/phpmyadmin

Cambiar los permisos de /usr/share/phpmyadmin para el usuario www-data y el grupo de trabajo www-data

chown -R www-data:www-data /usr/share/phpmyadmin

Posicionarnos en el directorio /etc/apache2/conf-available/

cd /etc/apache2/conf-available/

Crear el archivo phpmyadmin.conf en /etc/apache2/conf-available/

nano /etc/apache2/conf-available/phpmyadmin.conf

# phpMyAdmin default Apache configuration

Alias /phpmyadmin /usr/share/phpmyadmin

<Directory /usr/share/phpmyadmin>
    Options SymLinksIfOwnerMatch
    DirectoryIndex index.php

    <IfModule mod_php5.c>
        <IfModule mod_mime.c>
            AddType application/x-httpd-php .php
        </IfModule>
        <FilesMatch ".+\.php$">
            SetHandler application/x-httpd-php
        </FilesMatch>

        php_value include_path .
        php_admin_value upload_tmp_dir /var/lib/phpmyadmin/tmp
        php_admin_value open_basedir /usr/share/phpmyadmin/:/etc/phpmyadmin/:/var/lib/phpmyadmin/:/usr/share/php/php-gettext/:/usr/share/php/php-php-gettext/:/usr/share/javascript/:/usr/share/php/tcpdf/:/usr/share/doc/phpmyadmin/:/usr/share/php/phpseclib/
        php_admin_value mbstring.func_overload 0
    </IfModule>
    <IfModule mod_php.c>
        <IfModule mod_mime.c>
            AddType application/x-httpd-php .php
        </IfModule>
        <FilesMatch ".+\.php$">
            SetHandler application/x-httpd-php
        </FilesMatch>

        php_value include_path .
        php_admin_value upload_tmp_dir /var/lib/phpmyadmin/tmp
        php_admin_value open_basedir /usr/share/phpmyadmin/:/etc/phpmyadmin/:/var/lib/phpmyadmin/:/usr/share/php/php-gettext/:/usr/share/php/php-php-gettext/:/usr/share/javascript/:/usr/share/php/tcpdf/:/usr/share/doc/phpmyadmin/:/usr/share/php/phpseclib/
        php_admin_value mbstring.func_overload 0
    </IfModule>

</Directory>

# Disallow web access to directories that don't need it
<Directory /usr/share/phpmyadmin/templates>
    Require all denied
</Directory>
<Directory /usr/share/phpmyadmin/libraries>
    Require all denied
</Directory>
<Directory /usr/share/phpmyadmin/setup/lib>
    Require all denied
</Directory>

Activar la configuración

sudo a2enconf phpmyadmin.conf

Crear un directorio dentro de /var/lib/phpmyadmin/tmp

mkdir -p /var/lib/phpmyadmin/tmp

Cambiar los permisos del directorio /var/lib/phpmyadmin/tmp

chown www-data:www-data /var/lib/phpmyadmin/tmp

Reiniciar el servicio del Apache2

systemctl reload apache2 o también /etc/init.d/apache2 reload

Corregir error de logeo del usuario root y phpmyadmin

crear usuario y contraseña para el usuario phpmyamdin

mysql -u root
CREATE DATABASE phpmyadmin DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
GRANT ALL ON phpmyadmin.* TO 'phpmyadmin'@'localhost' IDENTIFIED BY 'debian';
FLUSH PRIVILEGES;
EXIT;

Otorgar todos los permisos al usuario root

mysql -u root -p
use mysql;
GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' IDENTIFIED BY 'debian' WITH GRANT OPTION;
FLUSH PRIVILEGES;
EXIT;