Title: Call to undefined function: add_filter()
Last modified: August 18, 2016

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# Call to undefined function: add_filter()

 *  [j3r0m3](https://wordpress.org/support/users/j3r0m3/)
 * (@j3r0m3)
 * [21 years, 4 months ago](https://wordpress.org/support/topic/call-to-undefined-function-add_filter/)
 * Hi there,
    I just tried to upgrade my blog from 1.22 to 1.5. however, i am getting
   this
 * Fatal error: Call to undefined function: add_filter() in /home/linguagy/public_html/
   blog/wp-includes/default-filters.php on line 4
 * when i run /wp-admin/upgrade.php
 * What did i do wrong?
    I did follow Podz guide.

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Moderator [Matt Mullenweg](https://wordpress.org/support/users/matt/)
 * (@matt)
 * [21 years, 4 months ago](https://wordpress.org/support/topic/call-to-undefined-function-add_filter/#post-146066)
 * You must not have uploaded all the files correctly, that’s a basic function that’s
   loaded at the very beginning for WP.
 *  Thread Starter [j3r0m3](https://wordpress.org/support/users/j3r0m3/)
 * (@j3r0m3)
 * [21 years, 4 months ago](https://wordpress.org/support/topic/call-to-undefined-function-add_filter/#post-146127)
 * Sorry for the big hoo-ha.
    I realised that i had uploaded the wrong folder.
 * Idiot!!!
    Thanks for making me realise what a fool i am! 🙂

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘Call to undefined function: add_filter()’ is closed to new replies.

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 2 replies
 * 2 participants
 * Last reply from: [j3r0m3](https://wordpress.org/support/users/j3r0m3/)
 * Last activity: [21 years, 4 months ago](https://wordpress.org/support/topic/call-to-undefined-function-add_filter/#post-146127)
 * Status: not resolved

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