Commerce element query on custom field in console command
Found it: the reason for the Exception is, that the dynamic method productStartDate (coming from the CustomFieldBehavior) needs an Array as parameter.
I have no clue why I get this misleading Exception though...
So finally, this works:
use craft\commerce\elements\Product;
$product = Product::find()
                -&gt;type('ticket')
                -&gt;productStartDate(['&gt;=&quot;2021-01-01 00:00:00&quot;'])
                -&gt;all();