The secret passphrase in configuration (blowfish_secret) is too short. code example
Example: the configuration file now needs a secret passphrase (blowfish_secret)
cp /usr/share/phpmyadmin/config.sample.inc.php /usr/share/phpmyadmin/config.inc.php
$cfg['blowfish_secret'] = 'KLS$vbc91Lkja$vc@opGbxA278EWopdc';