OpenCart Community

I have a problem with user adding a product into cart.
I've installed opencart 3.0.2.0
If I add any product in cart it shows
<b>Notice</b>: Undefined property: proxy::getdefaultseller in
<b>/.../system/storage/modification/system/engine/action.php</b> on line <b>79</b>

Pretty sure "getdefaultseller" is not a standard OpenCart function. That means it's coming from a mod you've installed (maybe a multi-vendor extension?) so you should contact its developer for support. It's unlikely anyone here will know the solution for the issue.