What is the problem with editing pages in WordPress that is causing the fatal error message "Call to undefined function wp_theme_has_theme_json()"?

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The problem with editing pages in WordPress that is causing the fatal error message "Call to undefined function wpthemehasthemejson()" is due to the theme that is being used not being compatible with the WordPress version being used. The theme's functions.php file is attempting to use a function (wpthemehasthemejson()) that does not exist in the version of WordPress being used. This can occur when the WordPress version is updated, but the theme is not.