Nezobrazují se php

Měl jsem funkční stránky na localhost. Upgradoval jsem UBUNTU a zřejmě se něco nabořilo a nejsem schopen odhalit co.
Problém je následující:
- na umístění localhost jsou dva adresáře - v prohlížeči se zobrazují -
- vstoupím-li do adresáře, tak se již nic nezobrazí, ačkoliv soubory tam jsou -
- dále, přidám-li do umístění localhost textový soubor, tak ho lze zobrazit -
- a toto vůbec nechápu: přidám-li do umístění localhost soubor.php, tak se nezobrazí nic a nejsou vidět ani ty dva zmiňované adresáře!
joomla nefunguje a nelze spustit ani její administraci.

Co je to za problém? Poraďte prosím, kam sahnout, co zkontrolovat?

Zkuste odinstalovat celý LAMP (tedy Apache, MySQL a PHP) a pak znovu nainstalovat pomocí návodu zde .

nebo zkuste XAMPP .

Odinstaloval jsem, komplet, znovu nainstaloval, ale chová se to bohužel stejně.
Založil jsem tento soubor:
echo "ServerName localhost" | sudo tee /etc/apache2/conf.d/fqdn
Tento soubor to zobrazí.
"Skočím-li" do localhost/joomla, tak jen zcela bílá stránka

log sougor problémy hlásí, ale bohužel tomu nerozumím, můžete prosím pomoci?

PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/gd.so' - /usr/lib/php/20151012/gd.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/mbstring.so' - /usr/lib/php/20151012/mbstring.so: cannot open shared object file: No such file or directory in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/mcrypt.so' - /usr/lib/php/20151012/mcrypt.so: cannot open shared object file: No such file or directory in Unknown on line 0
[Tue Nov 01 03:41:21.313491 2016] [mpm_prefork:notice] [pid 1306] AH00163: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations
[Tue Nov 01 03:41:21.313548 2016] [core:notice] [pid 1306] AH00094: Command line: '/usr/sbin/apache2'
[Tue Nov 01 03:43:12.728342 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.728438 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 466, referer: http://localhost/
[Tue Nov 01 03:43:12.728467 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.728492 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.728535 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.728562 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.728585 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.728627 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.728645 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.728662 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.783649 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.783716 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.783744 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.783768 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.783817 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Warning: Attempt to modify property of non-object in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.783858 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.783877 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.783894 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.783910 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.783928 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Warning: Attempt to modify property of non-object in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.783953 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.783970 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.783987 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.784003 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.784020 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Warning: Attempt to modify property of non-object in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.784054 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.784071 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.784088 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.784104 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.784121 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Warning: Attempt to modify property of non-object in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.784148 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.784165 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.784194 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 464, referer: http://localhost/
[Tue Nov 01 03:43:12.784211 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 469, referer: http://localhost/
[Tue Nov 01 03:43:12.784228 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Warning: Attempt to modify property of non-object in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.824953 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:12.825034 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Notice: Array to string conversion in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Registry.php on line 473, referer: http://localhost/
[Tue Nov 01 03:43:14.792568 2016] [:error] [pid 2497] [client 127.0.0.1:60366] PHP Fatal error: Cannot use Joomla\\String\\String as String because 'String' is a special class name in /var/www/html/joomla/libraries/vendor/joomla/registry/src/Format/Json.php on line 12, referer: http://localhost/

Děkuji za odhalení příčiny! Můžete prosím poradit, snad již v této záležitosti naposledy, jak aktualizovat Joomla, když mi nefunguje administrace?