Out of warranty recently upgraded to the latest version of WordPress Version 3.0.3! However, I got stucked with the error message:
Fatal error: Call to undefined method wpdb::tables() in /home/content/r/a/p/raphaelnikolai/html/out-of-warranty/wp-admin/includes/upgrade.php on line 1403
Believe me, I was scared to death after seeing this heart stopping error! I thought, I was going to lose this entire site!!! After doing some intensive troubleshooting, I found out that this error was due to an out-dated db.php (located in /wp-content) , which is created by the plugin DB Cache. I renamed it and viola, it worked immediately!
Note that after upgrading, you should disable DB cache and re-enable it. That should do it! Good luck! If still have issues feel free to leave a comment below and we will try our best to help you out.