Can’t create new pages Warning: Creating default object from empty value post

Hello, I have been trying to create a page since yesterday. I keep getting this error: ”
Warning: Creating default object from empty value in /home/csidbcom/public_html/olsenredesign/wp-admin/includes/post.php on line 713″.

So far I have done the following:
-Disabled all plugins
-Switched to default theme
-Disabled wp_debug
-Cleared browser cache
-Installed Site Health plugin.

So far nothing has worked. Any help is appreciated.