Currently, Osclass 4.1.1. There is no need and no possibility to upgrade to a more recent version. Couldn't find the changes on my own. Help solve the Fixed item price function problem, where 0 price was processed as "Check with seller" instead of "Free". How to fix this problem? Or at least tell me which file to watch.

Who should remeber that? 

You certainly do, since you don't want to generate competitors. For osclass also once also began to respond, and we all know how it ended)

It might be updated year ago or so, who would remember that.
But I would tip file you ade looking for could be ItenActions.php

Another thing) I'll try to look more closely

It might be updated year ago or so, who would remember that.
But I would tip file you ade looking for could be ItenActions.php

Excellent. And you said you don't remember.

$aItem[ 'price' ]    = Params::getParam('price') === '' ? null : Params::getParam('price');   // update 420, Params::getParam('price') ? : null;

Thanks for the help, keep it up!

Cool