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How to Fix Pluggable.php File Errors in WordPress

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Are you seeing a pluggable.php file error on your WordPress site?

Sometimes, when you add a code snippet on your site or activate a new plugin, you may get the pluggable.php file error.

In this article, we will show you how to easily fix pluggable.php file errors in WordPress.

Fix errors in pluggable.php file in WordPress

When and Why Do You See Pluggable.php Errors?

WordPress allows users and plugins to override certain core functions. These functions are located in the pluggable.php file.

If a WordPress plugin or a custom code snippet fails to correctly handle one of these functions, then you will see an error like this one:

Warning: Cannot modify header information – headers already sent by (output started at /home/username/demosite/wp-content/themes/mytheme/functions.php:1035) in /home/username/demosite/wp-includes/pluggable.php on line 1179

Example of an error in WordPress mentioning pluggable.php file

Sometimes, you may be able to continue working on your WordPress website with this or some other error still appearing in the admin area.

In the screenshot below, you can see an example of an error message inside the WordPress dashboard.

Error in WordPress admin area

Having said that, let’s take a look at how to easily fix the pluggable.php file error in WordPress.

How to Fix Pluggable.php File Errors in WordPress

The pluggable.php file is a core WordPress file. It’s never a good idea to edit the core WordPress file as your first option, even when there is an error pointing to it.

More likely than not, the error is coming from a different location.

In order to fix any error mentioning the pluggable.php file, just look at the first location mentioned in the error:

Warning: Cannot modify header information – headers already sent by (output started at /home/username/demosite/wp-content/themes/mytheme/functions.php:1035) in /home/username/demosite/wp-includes/pluggable.php on line 1179

In the above example, the error is located in the theme’s functions.php file at line 1035.

This means you just need to edit your theme’s functions.php file and change or remove the code causing this error.

Sometimes, the ‘headers already sent’ error is caused by an extra space after closing the php ?> tag, so you can just remove that, and it will fix the issue.

Let’s take a look at another example:

Warning: Cannot modify header information – headers already sent by (output started at /home/username/demosite/wp-content/plugins/some-plugin-name/some-plugin.php:144) in /home/username/demosite/wp-includes/pluggable.php on line 1090

This error message is pointing to a plugin on your WordPress site that is causing the error. You can simply deactivate the plugin and notify the plugin author about the error.

In almost all cases, errors mentioning the pluggable.php file are not caused by the file itself.

These errors are usually caused by a custom code snippet you added to the functions.php file, a poorly coded plugin, or even your WordPress theme.

Simply removing or editing the code or deactivating the plugin will make the error go away.

Still can’t figure out what’s causing these errors?

You can follow the instructions in our step-by-step guide for troubleshooting WordPress errors. It will help you find out the cause of the error and how to fix it quickly.

Bonus: Use WPCode to Insert Code Snippets in WordPress

Sometimes, you can cause pluggable.php file errors and other WordPress errors by inserting custom code into your functions.php file. In the worst-case scenario, the code snippet can even break your website.

That’s why we recommend using WPCode instead. It’s the best WordPress code snippets plugin that allows you to add custom code to your website without breaking it.

WPCode - Best WordPress Code Snippets Plugin

First, you will need to install and activate the WPCode plugin. For detailed instructions, see our tutorial on how to install a WordPress plugin.

Upon activation, visit the Code Snippets » + Add Snippet page from the WordPress dashboard. Here, you can click the ‘Use Snippet’ button under the ‘Add Your Custom Code (New Snippet)’ option.

You can also use the premade code snippets that are a part of the WPCode library.

Add a new code snippet in WPCode

This will open the ‘Create Custom Snippet’ page where you can add a name for the code snippet. After that, you can select the code type from the dropdown menu on the right.

Next, add the custom code into the ‘Code Preview’ box and toggle the ‘Inactive’ switch to ‘Active’.

Save the code snippet

Finally, click the ‘Save Snippet’ button to store your settings. You have now successfully added custom code to your website.

For more details, you can see our guide on how to easily add custom code in WordPress.

We hope this article helped you resolve pluggable.php file errors in WordPress. You may also want to bookmark our list of the most common WordPress errors and how to fix them and see our expert picks for the best code editors for editing WordPress files.

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Editorial Staff

Editorial Staff at WPBeginner is a team of WordPress experts led by Syed Balkhi with over 16 years of experience in WordPress, Web Hosting, eCommerce, SEO, and Marketing. Started in 2009, WPBeginner is now the largest free WordPress resource site in the industry and is often referred to as the Wikipedia for WordPress.

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Reader Interactions

51 CommentsLeave a Reply

  1. Syed Balkhi says

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  2. Rinto says

    I am very new to WordPress development, and this post guide me on the right way about the pluggable functions.

  3. Larry Donald says

    Hi, Thanks for the insight. I had a similar error preventing me from logging into my admin area. The page was just blank.

    Warning: Cannot modify header information

    I followed your instruction on case one, removing a space after the PHP closing tag and it worked out for me

  4. Stephanie Tognetti says

    I can’t log in to my admin page at all. I know exactly how to fix it, but I can’t log in. How can I access my page if it won’t let me log in through the WordPress login page?

  5. Sixtus says

    Thanks for this useful information. I just followed your guide and was able to fix the error. Indeed, am grateful.

  6. Perrin Brunson says

    I was about to lose my mind trying to figure out what was wrong, and that extra space was all it was! Thank you thank you thank you!

    • Shane says

      Same here!

      It was driving me crazy…. All it was was the first blank line above the <?php in my customizer.php file…..


      thank you WPBeginner Editorial Staff !!!

  7. Dave CJ says

    This article is super helpful and actually resolved the error on my wordpress install. It was additional space in functions.php.

    Thanks a lot team. Keep up the great work.

  8. James says

    This step worked for me..
    “Sometimes the headers already sent error is caused by an extra space after closing the php ?> tag, so you can just remove that, and it will fix the issue.”

  9. angela says

    Hi, I see a message like that. I was trying to update my theme when the message appeared. The problem is that the message blocks the access to my dashboard. I mean, it doesn’t even allow me to log in to my dashboard anymore!!! what can I do? this is the message: Warning: Cannot modify header information – headers already sent by (output started at /home3/angelasobral/public_html/wp-content/themes/glowline/inc/static-function.php:238) in /home3/angelasobral/public_html/wp-includes/pluggable.php on line 1210
    Thank you so much for your help

  10. Vijay Patel says

    Thank you very much for the really helpful article. I faced an error occuring in my website because of the Comment Code just after PHP start tag <?php
    something like this…

    Plugin Name: Some Name
    Plugin URI:
    Description: Some Description
    Author: Author Name
    Author URI:
    Version: 2.1

    I removed comment part and it solved my problem.

    Thanks a lot for the help. :)

  11. Deborah says

    THANK YOU SO MUCH! my programmer left an extra space before AND after the <php? tag. now it works just fine!

  12. prathapreedy says

    Thank you information about this error. I need complete guide on how split post into pages

  13. Matty R says

    Ah that empty space after ?> closing tag…. Never would have guessed it. Thank you sir! You saved me a lot of time and frustration.

  14. RickH says

    Developing a plugin, and added the wp_safe_redirect call to the plugin. Getting an ‘function wp_safe_redirect’ not found error.

    I think this is because pluggable.php is not loaded until *after* the plugin. Is this correct, and how do I fix it?

  15. Jason Teale says

    This error is killing me! I deactivated the plugins and it is got the site up but I can’t access the admin area. Getting this:

    Warning: Cannot modify header information – headers already sent by (output started at /home/content/f/i/n/finmadden/html/wp-includes/class-walker-page.php:1) in /home/content/f/i/n/finmadden/html/wp-includes/pluggable.php on line 1179

    any thoughts?

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