Estou com o mesmo erro, depois desinstalei tudo com
sudo apt-get purge phpmyadmin*
depois usei esse comando que vocês falaram:
sudo apt-get install php-gettext php-mbstring
depois instalei de novo:
sudo apt-get -y install phpmyadmin
E continua não funcionando, meu log de erros abaixo (tá meio grande porque eu tentei umas 3 vezes):
[Thu Aug 18 22:51:33.146110 2016] [core:notice] [pid 20665] AH00094: Command line: '/usr/sbin/apache2'
[Thu Aug 18 23:14:19.638149 2016] [mpm_prefork:notice] [pid 20665] AH00169: caught SIGTERM, shutting down
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/php_pdo_mysql.dll' - /usr/lib/php/20151012/php_pdo_mysql.dll: cannot open shared object file: No such file or directory in Unknown on line 0
[Thu Aug 18 23:14:20.807335 2016] [mpm_prefork:notice] [pid 21145] AH00163: Apache/2.4.18 (Ubuntu) configured -- resuming normal operations
[Thu Aug 18 23:14:20.807365 2016] [core:notice] [pid 21145] AH00094: Command line: '/usr/sbin/apache2'
[Thu Aug 18 23:17:32.984684 2016] [mpm_prefork:notice] [pid 21145] AH00169: caught SIGTERM, shutting down
[Thu Aug 18 23:17:34.140683 2016] [ssl:warn] [pid 21264] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/php_pdo_mysql.dll' - /usr/lib/php/20151012/php_pdo_mysql.dll: cannot open shared object file: No such file or directory in Unknown on line 0
[Thu Aug 18 23:17:34.168034 2016] [ssl:warn] [pid 21265] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Thu Aug 18 23:17:34.169124 2016] [mpm_prefork:notice] [pid 21265] AH00163: Apache/2.4.18 (Ubuntu) OpenSSL/1.0.2g-fips configured -- resuming normal operations
[Thu Aug 18 23:17:34.169136 2016] [core:notice] [pid 21265] AH00094: Command line: '/usr/sbin/apache2'
[Thu Aug 18 23:17:39.140310 2016] [mpm_prefork:notice] [pid 21265] AH00169: caught SIGTERM, shutting down
[Thu Aug 18 23:17:40.218732 2016] [ssl:warn] [pid 21324] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/php_pdo_mysql.dll' - /usr/lib/php/20151012/php_pdo_mysql.dll: cannot open shared object file: No such file or directory in Unknown on line 0
[Thu Aug 18 23:17:40.240909 2016] [ssl:warn] [pid 21325] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Thu Aug 18 23:17:40.242084 2016] [mpm_prefork:notice] [pid 21325] AH00163: Apache/2.4.18 (Ubuntu) OpenSSL/1.0.2g-fips configured -- resuming normal operations
[Thu Aug 18 23:17:40.242096 2016] [core:notice] [pid 21325] AH00094: Command line: '/usr/sbin/apache2'
[Thu Aug 18 23:17:56.945310 2016] [mpm_prefork:notice] [pid 21325] AH00171: Graceful restart requested, doing restart
AH00558: apache2: Could not reliably determine the server's fully qualified domain name, using 127.0.1.1. Set the 'ServerName' directive globally to suppress this message
PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php/20151012/php_pdo_mysql.dll' - /usr/lib/php/20151012/php_pdo_mysql.dll: cannot open shared object file: No such file or directory in Unknown on line 0
[Thu Aug 18 23:17:56.970593 2016] [ssl:warn] [pid 21325] AH01909: 127.0.1.1:443:0 server certificate does NOT include an ID which matches the server name
[Thu Aug 18 23:17:56.970681 2016] [mpm_prefork:notice] [pid 21325] AH00163: Apache/2.4.18 (Ubuntu) OpenSSL/1.0.2g-fips configured -- resuming normal operations
[Thu Aug 18 23:17:56.970685 2016] [core:notice] [pid 21325] AH00094: Command line: '/usr/sbin/apache2'