I'm disappointed to see that Ubuntu18 (Bionic) is shipping with multiple outdated packages which have PHP 7.2 compatibility issues (I'm having the same or worse issue with php-tcpdf, see bug#1781000) but the quickest solution seems to be to go upstream for current versions of the affected code.
The latest version is https:/ /files. phpmyadmin. net/phpMyAdmin/ 4.8.2/phpMyAdmi n-4.8.2- all-languages. tar.gz - just grab it from phpMyAdmin's site and drop it in your /var/www/html tree.
I'm disappointed to see that Ubuntu18 (Bionic) is shipping with multiple outdated packages which have PHP 7.2 compatibility issues (I'm having the same or worse issue with php-tcpdf, see bug#1781000) but the quickest solution seems to be to go upstream for current versions of the affected code.