Major Upgrading Errors

I tried to upgrade to 2.3 today and now I’ve run into a ton of errors.

My child categories have disappeared and only the parent remains.

Here’s one that I get on the front page:

WordPress database error: [Table ‘stuffwel_wrdp3.wp_categories’ doesn’t exist]
SELECT cat_name FROM wp_categories ORDER BY cat_name ASC

Then when I go to post, I get this message:

WordPress database error: [Table ‘stuffwel_wrdp3.wp_post2cat’ doesn’t exist]
SELECT cat_ID AS ID, MAX(post_modified) AS last_mod FROM wp_posts p LEFT JOIN wp_post2cat pc ON p.ID = pc.post_id LEFT JOIN wp_categories c ON pc.category_id = c.cat_ID WHERE post_status = ‘publish’ GROUP BY cat_ID

WordPress database error: [Table ‘stuffwel_wrdp3.wp_post2cat’ doesn’t exist]
SELECT cat_ID AS ID, MAX(post_modified) AS last_mod FROM wp_posts p LEFT JOIN wp_post2cat pc ON p.ID = pc.post_id LEFT JOIN wp_categories c ON pc.category_id = c.cat_ID WHERE post_status = ‘publish’ GROUP BY cat_ID

Warning: Cannot modify header information – headers already sent by (output started at /home/stuffwel/public_html/stuffwelike/wp-includes/wp-db.php:160) in /home/stuffwel/public_html/stuffwelike/wp-includes/pluggable.php on line 391

Any idea how to fix these?

My blog is https://www.stuffwelike.com/stuffwelike

Thanks!