MODX EVO 1.2.1 upgraded to PHP7

Hi

any help would be appreciated. we switched a modx 1.2.1 from php5.6 to php7 to see if it would float and it didn't. the error log received:


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[20-Sep-2017 13:40:10 UTC] PHP Fatal error: Uncaught Error: Class 'mysqli' not found in /home/ggmservices/public_html/domain.com/manager/includes/extenders/dbapi.mysqli.class.inc.php:29
Stack trace:
#0 /home/ggmservices/public_html/domain.com/manager/includes/document.parser.class.inc.php(2028): DBAPI->connect()
#1 /home/ggmservices/public_html/domain.com/index.php(128): DocumentParser->executeParser()
#2 {main}
thrown in /home/ggmservices/public_html/domain.com/manager/includes/extenders/dbapi.mysqli.class.inc.php on line 29
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We presumed that evo 1.2.1 was php7 friendly already and had the mysql1 classes etc, and that we wouldn't be missing classes. anyone come across errors like this when they moved to php7?

thanks

John