Hello,
as a wordpress newbie some days of search work were necessary until I found the reason that I could not make any changes to my homepage even as an administrator (but at least I got to know WP quite well through this 
) !
The error messages I received from WP were:
WordPress database error: [Unknown column ‘post_content_filtered’ in ‘field list’]
INSERT INTO s47ur5l5_posts (post_author, post_date, post_date_gmt, post_content, post_content_filtered, post_title, post_excerpt, post_status, post_type, comment_status, ping_status, post_password, post_name, to_ping, pinged, post_modified, post_modified_gmt, post_parent, menu_order, post_mime_type, guid) VALUES (8, ‘2021-10-09 22: 46:07’, ‘0000-00-00 00:00:00’, ”, ”, ‘auto-saved draft’, ”, ‘auto-draft’, ‘post’, ‘closed’, ‘open’, ”, ”, ”, ‘2021-10-09 22:46:07’, ‘0000-00-00 00:00:00’, 0, 0, ”, ”)
Notice: Trying to get property ‘post_type’ of non-object in /homepages/1/d886546666/htdocs/Apariv/wp/wp-admin/includes/post.php on line 697
Warning: Creating default object from empty value in /homepages/1/d886546666/htdocs/Apariv/wp/wp-admin/includes/post.php on line 736
Notice: Undefined property: stdClass::$ID in /homepages/1/d886546666/htdocs/Apariv/wp/wp-admin/includes/dashboard.php on line 552
Notice: Undefined property: stdClass::$ID in /homepages/1/d886546666/htdocs/Apariv/wp/wp-admin/includes/dashboard.php on line 556
Checking the database revealed that simply the ‘post_content_filtered’ field is missing from the ‘posts’ table.
Since I did not edit the database directly, nor did I make any changes to the php files, the question I have is, during which upgrade did this error occur (WP upgrades are done automatically)?
In addition, of course, I do not know if the listed php-files work correctly!
What will happen if I add the missing field in the table?
or how can I determine the integrity of the installed system and remove integrity violations???
Need therefore urgent help that even a wordpress newbie can implement!!!
Thanks in advance
Arnold