Title: WordPress upgrade causing an error
Last modified: August 21, 2016

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# WordPress upgrade causing an error

 *  Resolved [applegateian](https://wordpress.org/support/users/applegateian/)
 * (@applegateian)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/)
 * Hi guys
 * I am a bit stuck. Since trying to carry out the automatic upgrade to 3.6 my site
   threw the following error:
 * `Warning: call_user_func_array() [function.call-user-func-array]: First argument
   is expected to be a valid callback, '_show_post_preview' was given in /websites/
   123reg/LinuxPackage21/an/ne/tt/annettenix.com/public_html/adminarea/wp-includes/
   plugin.php on line 406`
 * The theme is called Craft from ThemeTrust.
 * I had a look at plugin.php but couldn’t see anything obvious, any thoughts?
 * Thanks,
 * Ian

Viewing 7 replies - 1 through 7 (of 7 total)

 *  [esmi](https://wordpress.org/support/users/esmi/)
 * (@esmi)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078634)
 * Can you replicate the problem using the default Twenty Thirteen theme with **
   all** other plugins deactivated?
 *  Thread Starter [applegateian](https://wordpress.org/support/users/applegateian/)
 * (@applegateian)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078640)
 * Annoyingly, the default theme was removed. I can’t add a new theme through the
   site, presumably I could upload Twenty Thirteen via FTP to test it?
 *  Thread Starter [applegateian](https://wordpress.org/support/users/applegateian/)
 * (@applegateian)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078642)
 * Tried uploading TwentyTen but live preview is showing me:
 * > Fatal error: Call to undefined function get_post_format_slugs() in /websites/
   > 123reg/LinuxPackage21/an/ne/tt/annettenix.com/public_html/adminarea/wp-includes/
   > theme.php on line 1262
 * _[[No bumping](http://codex.wordpress.org/Forum_Welcome#No_Bumping). This is 
   a volunteer-staffed forum – not real-time chat. If it’s that urgent, consider
   [hiring someone](http://directory.codepoet.com/).]_
 *  [esmi](https://wordpress.org/support/users/esmi/)
 * (@esmi)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078710)
 * What version of WordPress are you running?
 *  Thread Starter [applegateian](https://wordpress.org/support/users/applegateian/)
 * (@applegateian)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078711)
 * Looks like 3.5.1 -thanks
 *  [esmi](https://wordpress.org/support/users/esmi/)
 * (@esmi)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078713)
 * Why are you using an old copy of WordPress? Were you aware that your site is 
   currently running a very real risk of being hacked? You need to upgrade WordPress
   asap. by:
 * – switching to the default theme by renaming your current theme’s folder inside
   wp-content/themes and adding “-old” to the end of the folder name using [FTP](http://codex.wordpress.org/FTP_Clients)
   or whatever file management application your host provides.
 * – [resetting the plugins folder](http://codex.wordpress.org/FAQ_Troubleshooting#How_to_deactivate_all_plugins_when_not_able_to_access_the_administrative_menus.3F)
   by FTP or phpMyAdmin.
 * – re-uploading all files & folders – **except** the wp-content folder – from 
   a **fresh** download of WordPress. Make sure that you delete the old copies of
   files & folder before uploading the new ones.
 * – running the upgrade manually via wp-admin/upgrade.php
 *  Thread Starter [applegateian](https://wordpress.org/support/users/applegateian/)
 * (@applegateian)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078724)
 * That worked perfectly esmi, thanks so much for the suggestion
 * (I don’t manage the site, just helping out!)

Viewing 7 replies - 1 through 7 (of 7 total)

The topic ‘WordPress upgrade causing an error’ is closed to new replies.

## Tags

 * [call_user_func_array](https://wordpress.org/support/topic-tag/call_user_func_array/)
 * [themetrust](https://wordpress.org/support/topic-tag/themetrust/)
 * [upgrade](https://wordpress.org/support/topic-tag/upgrade/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 7 replies
 * 2 participants
 * Last reply from: [applegateian](https://wordpress.org/support/users/applegateian/)
 * Last activity: [12 years, 9 months ago](https://wordpress.org/support/topic/wordpress-upgrade-causing-an-error/#post-4078724)
 * Status: resolved

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