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?

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?