Try to create a new page this shows: Creating default object from empty value in

Hello,

For around 5 hours, I have been unable to create a new page on my website as the warning message “Creating default object from empty value in /home/customer/www/mywebsite.com/public_html/wp-admin/includes/post.php on line 742” pops up. This is the line of code that pops up when I go to my website hosting and look in the wp-admin folder, then the includes folder, then the post.php folder and scroll down to line 742: “$post->post_content = (string) apply_filters( ‘default_content’, $post_content, $post );”

I have downloaded the health check and troubleshooting plugin and have concluded that there is no problem with my theme or other plugins; I used the troubleshooting from this plugin and deactivated all the plugins, as well as changed the theme to twenty-twenty-two, and the same warning message came up regardless. I even went as far as to completely delete the line of code from my website hosting and still got the same message. I did also clear my cache and cookies and logged out of my WordPress dashboard to no avail. Is there a solution?

Thanks in advance.
P.S. I’m nervous about manually upgrading as I don’t understand how that works and would not like to lose a bunch of work I put into creating my website.