Roundcube fatal error via Undefined class constant 'MYSQL_ATTR_FOUND_ROWS'

I'm running ispConfig3 on Debian 9 Stretch with nginx, having followed the multi-server instructions to install a slave server for websites and their email. Getting squirrelmail/roundcube up is causing some headaches. When I go to host.tld/squirrelmail/ I get a 500 error. The server logs show:

Code:

PHP Fatal error:  Uncaught Error: Undefined class constant 'MYSQL_ATTR_FOUND_ROWS' in /usr/share/roundcube/program/lib/Roundcube/rcube_db_mysql.php

Searches have revealed that one should have php-mysql and PDO installed, which I do.

Code:

php -m | grep -i pdo
PDO
pdo_mysql

Any helpful suggestions how to fix this appreciated. (fixed see below)

 

Never mind, I think I figured out what's going on. I had both php7.0 and php7.3 installed. The web interface under /squirrelmail/ was using php7.0 apparently, which was messing with the much more complete and up-to-date php7.3 installation. Thus the error.

It seems nearly impossible to get rid of php7.0 (just btw.) and yes, I've tried

Code:

apt-get remove -purge php7.0

but this still leaves loads of php7.0 stuff scattered around the system. Which in turn leads to situations like this where one is using 7.3 everywhere and then 7.0 steps in and screws you over. Ah well, something else learnt

 

thanks for the tip, Till, that would explain why I was struggling with the older version. I'll be upgrading as soon as I dare. I presume there are no issues with ispConfig for a clean debian 9 -> 10 dist-upgrade.

ps. s/sues/uses/