EnglishThe "Headers already sent" error in WordPress occurs when something in your code or configuration has sent output to the browser before WordPress had a chance to send HTTP headers. This can be caused by extra spaces, new lines, or even non-PHP content outside the PHP tags (<?php ?>). Here's how to troubleshoot and fix this issue:
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Check for Whitespace or Extra Characters:
- Make sure there are no spaces, new lines, or any content before the opening
<?phptag or after the closing?>tag in your files. This includes in your theme'sfunctions.phpfile, plugins, and even in yourwp-config.phpfile.
- Make sure there are no spaces, new lines, or any content before the opening
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Disable Browsing Caching:
- If you're using a caching plugin or server-side caching, try disabling it temporarily to see if it resolves the issue. Cached content can sometimes cause headers to be sent prematurely.
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Check for Error Messages:
- If you're getting specific error messages along with the "Headers already sent" message, pay close attention to them. They might give you clues about the source of the issue.
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Review Recent Changes:
- If the error started occurring after you made changes (installed a plugin, updated a theme, etc.), try reverting those changes to see if it resolves the issue.
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Enable WP_DEBUG:
- Add the following lines to your
wp-config.phpfile to enable debugging and log any PHP errors:
php - Add the following lines to your
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define('WP_DEBUG', true); define('WP_DEBUG_LOG', true);This will create a
debug.logfile in yourwp-contentdirectory with error messages. -
Check for Plugin/Theme Conflicts:
- Temporarily deactivate all plugins and switch to a default WordPress theme (like Twenty Twenty-One). If the error disappears, reactivate each plugin/theme one by one to identify the one causing the conflict.
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Check for Byte-Order Marks (BOM):
- Some text editors can add a Byte-Order Mark at the beginning of PHP files which can cause this issue. Use a text editor that doesn't add BOM or remove it manually if it exists.
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Check for Blank Lines at the End of Files:
- Make sure there are no extra blank lines after the closing
?>tag in your PHP files.
- Make sure there are no extra blank lines after the closing
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Check File Encoding:
- Ensure that your PHP files are encoded as UTF-8 without a BOM. Some text editors allow you to set the file encoding.
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Reinstall WordPress Core Files:
- If none of the above steps work, consider reinstalling the WordPress core files. Make sure to backup your database and files before doing so.
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Contact Hosting Provider:
- If the issue persists, it's possible there might be a server-level problem. Contact your hosting provider for further assistance.
Remember to always back up your website files and database before making any significant changes. This way, you can easily restore your site if something goes wrong during troubleshooting.
