Why does the PHP header redirect not work sometimes?

Ever stuck hours or days looking for bugs in your PHP project when the redirection is not working as expected?

I felt the same while working on a project for my new PHP course. And after looking for possible bugs for some time, I remembered the fix I used when I was just a beginner (a decade ago).

Then I tried it and it worked as expected.

Now I was curious to know why the PHP header was not working when another fix is working fine.

So I did a quick Google search and found out that there should not be any output (like HTML, whitespace or errors) before header() function call. It’s similar to the “Cannot modify header information” error.

Possible Causes of Header Errors

1. Whitespace before opening PHP tag: Any space or new line before the opening “<?php” tag is considered as an output.

2. HTML output before Header call: Any echo/print statements that have been executed before header redirection also can cause the issue.

3. URL issue: The URL you pass on the header function must be properly formatted. Any type error (misspelling) can also prevent header from properly redirecting.

4. Dropped HTML Comments: HTML comments that are misplaced and rendered before the header call also can cause the error.

How to fix the header not redirecting issue on PHP?

There are few quick fixes to the header not redirecting issue on PHP that I have personally used in my projects. Let’s explore them

1. Buffer Output

One of the essential features in PHP is Output Buffering which temporarily stores output before sending it to the browser. Usually PHP sends output (like HTML, echo statements, etc.) immediately and into pieces. But with Output buffering, it sends the output data altogether to the browsing by compressing which improves performance in PHP applications and also prevents “headers already sent errors” or header redirection issues.

How to fix header redirection issue with Buffer Output?

To fix the header redirection issue with Buffer Output in PHP, you just need to add “ob_start()” function at the top of your page as soon as PHP tag opens “<?php” .

For example:

<?php 

ob_start(); // Start Output Buffering

echo “Output Buffering Started”;

header(‘location:https://vijaythapa.com.np/’);

// And all other PHP code

?>

2. Use JavaScript Redirection

Another quick and easy fix is to redirect with JavaScript. You can just use the “window.location” function in your script.

For example:

<?php 

echo "<script type='text/javascript'>  window.location='https://vijaythapa.com.np/'; </script>";

?>

3. Use “Exit” after redirect calls

Similarly, you can also use ‘exit()’ PHP function after the header() redirection which prevents any accidental output that could mess up the redirection process.

For example: 

<?php 

header(‘location:https://vijaythapa.com.np/’);

exit();

// And all other PHP code

?>

It can sometimes be irritating and time consuming to manage redirection in PHP. But by following the best practices discussed in this article (like output buffering, using exit(), etc.) you can mitigate the headaches and complete your web application while maintaining effective control over user navigation.

But if you’re still facing the header redirection issues, then comment below or email me with the screenshot of your code at [email protected].