How to Fix Pluggable.php File Errors in WordPress

Fix Pluggable.php File Errors in WordPress: WordPress website owners may encounter a “pluggaple.php file error” when including a custom code or code snippet to their website or installing and activating a WordPress plugin. While this error is less typical, several users report it when modifying their website.

Moreover, among several other errors, the pluggable.php error may seem a bit tricky to deal with. When handling this crisis, you may wonder what this error is, why you see this error, and how you can fix it. For this purpose, this article offers comprehensive information to answer all your queries.

How to Identify a Pluggable.php File Error?

To identify the pluggable.php error, you must know what it looks like. If you notice something like the following, you may be dealing with a pluggable.php file error:

Warning: Cannot modify header information – headers already sent by (output started at /home/username/yourwebsite/wp-content/themes/themename/admin-functions.php:109) in /home/username/yourwebsite/wp-includes/pluggable.php on line 1179

Here, the “username” will be your hosting account’s name, and the “yourwebsite” will have the file name of the location that stores your website. The warning message with the error indicates where the error is.

The “admin-functions.php” is where the document for your theme needs fixing where the error occurs on line 109. This error will state the theme’s name. The error message can also indicate an error with the recently installed plugin.

Reason Behind Pluggable.php Errors

WordPress consists of a pluggable.php file, which you can locate in the wp-includes folder. WordPress admin can override this file, which comprises the WordPress core functions. Some of these pluggable functions include:

  • wp_mail – It helps deliver emails. You may alter this to personalize the email template for WordPress.
  • wp_new_user_notification – Use this to send emails to newly registered users instantly.
  • wp_password_change_notification – Sends email to notify password changes.
  • auth_redirect – Sees if a user signed into the website. If not, it helps redirect them.

The pluggable.php file comprises a couple more functions with specific purposes. You may override or alter these functions during customization. When overriding a function via a code snippet or plugin, you may notice the pluggable.php error. This error appears when your code snippet or plugin cannot override the WordPress pluggable functions.

How to Resolve the Pluggable.php File Errors in WordPress?

Fixing the error of pluggable.php does not have to be so arduous. All you need is the location where the error occurred. You can easily find the error location by assessing the error message your screen is showing. Once you read the error, you can familiarize yourself with the following steps you need to take to resolve the error.

  • Backup Your Files

Among the various critical WordPress Themes files, the pluggable.php file handles numerous functions of your WordPress site. So, before you head down the path of resolving the error, you must make a backup for all your website files.

  • Manually Edit Corrupted Files

The first step to fixing the “Warning: cannot modify header information” includes editing the defective file yourself. The error message supplies you with the required details to identify the location of the problem. It will be the first file you notice in the error message.

You can use an FTP client, like File Manager or FileZilla, to access the file concerned. Notice the PHP tags at the beginning and end, and ensure there are no spaces preceding or after the “<?php” and “?>” tags. Also, check that there is no extra space or blank line after the final code statement.

  • Check Custom Code

Thanks to WordPress, it is easy for users to incorporate code snippets into various fundamental website files without difficulty. Therefore, if you tend to introduce new code snippets to the files from unsupported sources, you may face tribulation finding them.

Hence, you can encounter this error when you alter crucial files by incorporating a new code snippet. You must retrace back to the root directory and find the file using an FTP client. After downloading the file, you can access and analyze it using a text editor.

The notification error will determine the line consisting of the error. It will also specify the error code and the error location. Once you locate the custom code, you can eliminate it, save the file, and upload it to the root directory with the aid of an FTP client. Reloading the website will solve this error.

  • Remove Extra Spaces

Among the several coding mistakes, one that can lead to the pluggable.php error is the additional space after the closing “?>” php tag. If this is the case, you can remove any space to allow the smooth functioning of the code.

  • Deactivate Defective Plugin 

Have you recently downloaded a plugin to your WordPress site? Chances are it is disrupting the management of the core functions for your WordPress. If so, you must deactivate and notify the creator about the defective plugin.

Access your WordPress dashboard to find the “Plugins” tab to browse the “Installed Plugins” and locate the plugin creating the problem. Click the “Deactivate” option to resolve the issue. Next, refresh your website to notice the website is back to running normally. 

Another method to resolve this issue without the WordPress dashboard is via the FTP client. It will help you access the folder that stores your file. You can locate the plugins folder in the wp-content folder to find the one causing the error. Add “_deactivate” by renaming the folder’s name and reloading the site to see the error gone.

  • Deactivate the Theme 

If it isn’t the plugin, sometimes it is the theme causing the issue. If true, you may deactivate the theme by accessing your dashboard. Take your mouse cursor over “Appearance” and select “Themes.” The adjacent screen will display all the installed WordPress themes.

To deactivate this theme, you must first activate the default theme. If you do not have a dashboard, you can use an FTP client to access the folder consisting of your site files. Through this access, the wp-content and find the folder for themes.

Find the name of the theme causing the error and deactivate it by adding “_deactivate” to the file name. Refreshing the site will resolve the error.

You can checkout our blogs on How To Resolve Common WordPress Errors To resolve common issues.


You can solve the pluggable.php error yourself without facing any difficulty. Primarily, you must locate the file that causes the error by familiarizing yourself with the route. You do not have to take the course that leads to the pluggable.php error. Generally, the problem is in the plugin or theme, not the core files. You can use the above steps to resolve this error effectively.

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