Warning messages at the beginning of update of OJS to 3.0

Hello, I created empty database and imported into that database old database from OJS
I unpacked ojs3.0 and made necessary changes to config.inc.php
I also copied files from old public into ojs3.0 public folder
When I Started update I got the following warning messages:

please advise

Hi @vvucic,

Those are “strict” warnings. You can either ignore them, or suppress them by tweaking your PHP configuration. They shouldn’t cause any problems – they’re just cosmetic.

Alec Smecher
Public Knowledge Project Team

OK. Thanks a lot for guidance.