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Fix WordPress Fatal error: Call to undefined function

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If you get an error like this, there is a plugin or other function called in your theme which you don’t have. How do you fix this? There are a few ways: remove the code, error proof it, get the necessary plugin, or upgrade WordPress if necessary. In this quick WordPress tip post we’ll go over how to error proof these with a conditional tag and PHP function known as: function_exists.

If you get an error such as Fatal error: Call to undefined function the_title_attribute() you can simply replace any instance of the_title_attribute with the following:

<?php if (function_exists('the_title_attribute')) { the_title_attribute(); } ?>

In this case, you could also take it one step further by adding an else statement.

<?php if (function_exists('the_title_attribute')) { the_title_attribute(); } else { the_title(); } ?>

Before trying a new theme on a production site, make sure to preview your theme first, and then work out all the errors (if any).

About

Leland Fiegel was the original founder of ThemeLab. He is a web developer who loves WordPress and blogging.

  • John

    Hi ive just used:

    And it worked for that file where i was previously getting the Fatal error.

    Im now trying it for 2 sidebars of my theme so that i can place them into their own .php files.

    The sidebars are named leftsidebar and rightsidebar, so i use the code as above and put in get_leftsidebar and get_rightsidebar but it goes wrong somehow and the layout gets messed up, im not sure where i may be making the mistake here though, any ideas please?

    Thanks

    John

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  • http://www.inspiratus.org Doug Rekenthaler

    I’m suddenly getting this error message:

    Fatal error: Call to undefined function feed_content_type() in /home7/inspird6/public_html/wp-includes/feed.php on line 8

    I have replaced my feed.php file with the original WP source code and still am getting this error. Am I missing something?

  • http://tompbeck.com/wordpress Tom

    I’m really new to this…only dabbled in websites in college..trying to get this up for portfolio…what can I do to fix this?
    Fatal error: Call to undefined function wp_pagenavi() in /home/content/77/9421577/html/wordpress

    Thank you