I hope you are well today and thank you for your question.
Could you please tell me what problem you are facing using it on local web server?
Where are you getting this warning message?
This is a simple PHP warning, it is nothing to worry about!
Do you have WP_DEBUG set to true in your wp-config.php file?
If you do then please set it to false.
This will hide the warning messages and you will be able to use your site normally.