A pluggable.php file error can appear on both the frontend and the backend. To be more specific, it might appear in place of your homepage, or after you access your WordPress Admin Section. Even worse, it often appears on all pages of your website, similar to the white screen of death in WordPress, which makes it devastating for your website traffic and SEO. Lucky for you, it usually has to do with the most recent change you’ve made, and not hosting or any outside factors. With that said, let’s demonstrate how to fix pluggable.php file errors in WordPress.
Should I edit the pluggable.php file?
No, you shouldn’t edit the pluggable.php file in WordPress. In fact, this is the primary reason website owners make things significantly worse, often forcing them to use a backup plugin for WordPress for salvation. So, disregard that part of the error code completely. To clarify, pluggable.php is a file that contains core functions WordPress depends on. The error simply tells you which of the functions failed to load. The problematic file is elsewhere, with or without a file path pointing to it, and is listed in front of the pluggable.php part of the error.
Fixing pluggable.php file errors in WordPress: Common solutions
Now that you know not to modify pluggable.php, let’s see what you can modify. Here are a few things you can do to fix pluggable.php file errors in WordPress:
1. Disable active WordPress theme
Here’s a 2-step guide to determine if the currently installed WordPress theme is the problem:
1. Analyze pluggable.php code
Does your pluggable.php error resemble this example?
Warning: Cannot modify header information – headers already sent by (output started at /root/website-name/wp-content/themes/active-theme-name/functions.php:134) in
/root/websitename/wp-includes/pluggable.php on line 1080
2. Double-check the theme is the culprit
If it does, the error seems to be caused by your active WordPress theme, specifically line 134 in the functions.php file. Before you get to fixing it (step 3 below), disable the WordPress theme temporarily. If that gets rid of the pluggable.php file errors in WordPress, only then should you begin troubleshooting. For instructions, look at the headline titled Fixing the issue if a theme was the problem in the “Are you sure you want to do this” error fix guide.
2. Disable a WordPress plugin
Once again, here’s a quick way to check if a WordPress plugin you installed is the issue.
1. Examine the pluggable.php code
Does your pluggable.php error look similar to this?
Warning: Cannot modify header information – headers already sent by (output started at /root/website-name/wp-content/plugins/plugin-name/some-plugin-function.php:138) in
/root/website-name/wp-includes/pluggable.php on line 1154
2. Verify WordPress plugins caused the pluggable.php file error
If the answer is yes, a WordPress plugin(s) is/are the source of the problem. Once again, before you start troubleshooting, disable all WordPress plugins at once to double-check. Refer to the error fix guide we mentioned for themes, but use the instructions under the headline titled Fixing the problem if the plugin caused it.
3. Study most recent code snippets
Now that you know where the problem stems from, remember the last edits you made concerning it, particularly code snippets. Did you edit your website footer or modify the header? You could’ve also edited the functions.php file of the active WordPress theme, created a site-specific WordPress plugin, or used a third-party WordPress plugin to insert headers and footers. Regardless of the method, the error message will pinpoint a specific file and line you should check first. Then, expand your survey by checking the lines above and below it. To give you an example, a common source of the pluggable.php error is an accidental space, new row, or line break. This is prevalent in lines around the closing PHP tag (?>).
My pluggable.php file error isn’t specific. What do I do?
In rare cases, pluggable.php error manifests without the aforementioned details in front of it. In that case, you can enable WP Debug Mode. It’s a WordPress feature that lists PHP errors in a log file, acting as replacements for the error codes mentioned above. For instructions, check our “This site is experiencing technical difficulties“ error guide, more specifically, the How to use WordPress Debug Mode headline. The troubleshooting and solving part is identical.