SQL syntax errors after upgrading to 2.3

Forgive me if this has been addressed – I found similar errors, but none that seemed to be the same to mine.

I upgraded to version 2.3.1 via Fantastico, and now am receiving errors. I can access my blog only without the www prefix at https://the-f-word.org/blog/ , but even then I see this error:

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘221,220,219,218,217,216,215,214,213,212) ORDER BY post_id, meta_key’ at line 1]
SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN(,221,220,219,218,217,216,215,214,213,212) ORDER BY post

If I try to access my blog with the www. prefix at https://www.the-f-word.org/blog/, I can’t see the blog at all, only this error:

WordPress database error: [You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘221,220,219,218,217,216,215,214,213,212) ORDER BY post_id, meta_key’ at line 1]
SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN(,221,220,219,218,217,216,215,214,213,212) ORDER BY post_id, meta_key

I seem to get the same error regardless of the theme I use. I contacted my website hosting support, and they say this is a WordPress error. Does anyone have any suggestions on how to fix the errors?

Thank you,

Rachel