URL issues when moving a WP site to a new host

I’m moving a WP site that I didn’t manage to a new host I do. I’ve followed the process posted here:

1. Download your existing site files.
2. Export your database – go in to mySQL and export the database.
3. Move the backed up files and database into a new folder – somewhere safe – this is your site backup.
4. Log in to the site you want to move and go to Settings > General, then change the URLs. (ie from https://example.com/ tohttps://example.net ) – save the settings and expect to see a 404 page.
5. Download your site files again.
6. Export the database again.
7. Edit wp-config.php with the new server’s mySQL database name, user and password.
8. Upload the files.
9. Import the database on the new server.

Only I can’t do step #4, I don’t have access to change the URL for the old site and export files again. I have the exported database and files, and I’ve gone into the DB and manually changed the URLs, but its not working. I’m getting these errors below and can’t log into my site. Is it a URL problem or something else?
Warning: Missing argument 2 for wpdb::prepare(), called in /home3/brand/public_html/serivces/wp-content/plugins/category-icons-lite/caticons-lite.class.php on line 231 and defined in/home3/brand/public_html/serivces/wp-includes/wp-db.php on line 1154

Warning: Cannot modify header information – headers already sent by (output started at /home3/brand/public_html/serivces/wp-includes/wp-db.php:1154) in /home3/brand/public_html/serivces/wp-includes/pluggable.php on line 1179

Thanks for any insight!