Fixing WordPress Issue: Cannot modify header information - PHP error

If you are a WordPress user, you may have come across the error message "Cannot modify header information - headers already sent by" at some point. This error can occur for various reasons, but it is usually related to a PHP error in your WordPress site's code.

The error message is usually caused by whitespace or other characters that are outputted before the header information is sent. This can happen if there is a PHP error in your code that is outputting something to the browser before the header information is sent, or if there is whitespace at the beginning or end of your PHP files.

How to Fix the Error

There are several ways to fix the "Cannot modify header information" error in WordPress:

1. Check for whitespace: Make sure that there is no whitespace at the beginning or end of your PHP files. You can use a text editor that shows hidden characters to check for whitespace.
2. Check for PHP errors: Look for any PHP errors in your code that may be outputting something to the browser before the header information is sent. You can check your site's error logs or use a plugin like Debug Bar to help you find the error.
3. Use ob_start(): You can use the ob_start() function to buffer your output and prevent any output from being sent to the browser before the header information is sent.

By following these steps, you should be able to fix the "Cannot modify header information - headers already sent by" error in your WordPress site.

<?php
// Example of using ob_start()
ob_start();
// Your code here
?>

Conclusion

The "Cannot modify header information" error can be frustrating, but it is usually caused by a simple PHP error in your code. By following the steps outlined above, you should be able to fix the error and get your WordPress site back up and running smoothly.