Title: 2.1 Database Error
Last modified: August 18, 2016

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# 2.1 Database Error

 *  [mwselz](https://wordpress.org/support/users/mwselz/)
 * (@mwselz)
 * [19 years, 4 months ago](https://wordpress.org/support/topic/21-database-error/)
 * Just installed 2.1 on my [http://www.mattselznick.com](http://www.mattselznick.com)
   site, and this database error is listed at the very top of my page:
 * `
    WordPress database error: [Unknown column 'wp_post2cat.category_id' in 'on
   clause'] SELECT SQL_CALC_FOUND_ROWS wp_posts.* FROM wp_posts LEFT JOIN wp_catt_visibility
   ON (wp_post2cat.category_id = wp_catt_visibility.catt_ID) WHERE 1=1 AND (post_type
   = 'post' AND (post_status = 'publish' OR post_status = 'private')) AND (post_type
   = 'post' AND (post_status = 'publish' OR post_status = 'private')) ORDER BY post_date
   DESC LIMIT 0, 5
 * Could this be a plugin error? Any ideas? Thanks.

Viewing 4 replies - 1 through 4 (of 4 total)

 *  Thread Starter [mwselz](https://wordpress.org/support/users/mwselz/)
 * (@mwselz)
 * [19 years, 4 months ago](https://wordpress.org/support/topic/21-database-error/#post-509199)
 * Update: On more digging, my aforementioned problems seems to have to do with 
   Pages on my site… links to pages result in a 404, and this is the error on the
   admin section’s “page management” page:
 * `
    WordPress database error: [Unknown column 'wp_post2cat.category_id' in 'on
   clause'] SELECT wp_posts.* FROM wp_posts LEFT JOIN wp_catt_visibility ON (wp_post2cat.
   category_id = wp_catt_visibility.catt_ID) WHERE 1=1 AND (post_type = 'page' AND(
   post_status = 'publish' OR post_status = 'future' OR post_status = 'draft' OR
   post_status = 'private')) AND (post_type = 'page' AND (post_status = 'publish'
   OR post_status = 'future' OR post_status = 'draft' OR post_status = 'private'))
   ORDER BY menu_order DESC
 * This is bad..!
 *  Thread Starter [mwselz](https://wordpress.org/support/users/mwselz/)
 * (@mwselz)
 * [19 years, 4 months ago](https://wordpress.org/support/topic/21-database-error/#post-509202)
 * Okay, sorry for my panicking. Upgrading the plugin “Category Visibility” ([http://ryowebsite.com/?p=46](http://ryowebsite.com/?p=46))
   fixed it. Now I’m gonna go through and upgrade all my plugins…!
 *  [25kgbox](https://wordpress.org/support/users/25kgbox/)
 * (@25kgbox)
 * [19 years, 2 months ago](https://wordpress.org/support/topic/21-database-error/#post-509678)
 * i am having a similar proble, but i do not have the Category Visibility plugin.
 *  [pipedreamergrey](https://wordpress.org/support/users/pipedreamergrey/)
 * (@pipedreamergrey)
 * [19 years ago](https://wordpress.org/support/topic/21-database-error/#post-509707)
 * This problem can also be caused by the Side Blog plugin.

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘2.1 Database Error’ is closed to new replies.

## Tags

 * [database](https://wordpress.org/support/topic-tag/database/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 4 replies
 * 3 participants
 * Last reply from: [pipedreamergrey](https://wordpress.org/support/users/pipedreamergrey/)
 * Last activity: [19 years ago](https://wordpress.org/support/topic/21-database-error/#post-509707)
 * Status: not resolved

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