PHP Fatal error: Uncaught Error: Call to a member function fetchAll() on boolean

[klor]

I am using thebestpdowrapper on two Windows 10 machines that runs the same PHP version 7.2.0 and 7.2.9. My script works on one machine but fails on the other. The failing machine consistently gives me this error message:

PHP Fatal error: Uncaught Error: Call to a member function fetchAll() on boolean

It fails when doing INSERTs, UPDATEs, SELECTs and likely any other SQL statement. Vanilla PDO works fine on the "failing" machine - and the database tables do have data (as seen with vanilla PDO).
Code used:

$sql = "SELECT * FROM tbl";
DB::prepare($sql)->execute()->fetchAll();

Any ideas why?

thebestpdowrapper must have some implicit pre-requisites - what are these?