The primary reason for the 'Headers already sent' error is that you have sent output to the browser before sending HTTP headers. This can be due to echoing or printing anything before the header function calls, such as using echo or print statements before calling header().Another possible cause is

How do I fix: Check for Output Before Header Calls?

Step 1: Another way to fix this issue is to check if any output has been sent before calling header(). You can do this by using the output buffering functions or by checking if ob_start() has been called.Step 2: If you are using echo or print statements before your header calls, move them after the

Coding⏱️ 3 min read📅 2026-06-03

How to Fix: How to fix "Headers already sent" error in PHP

Q: Best Solutions to Fix It Disable Output Buffering?

Step 1: To fix this issue, you need to disable any output buffering that may be enabled in your PHP configuration. You can do this by adding ob_start() and ob_end_clean() around the section of your script where you are sending headers.Step 2: Make sure to add ob_start() before any output is sent and

Headers already sent error in PHP occurs when output is sent before headers are set. To fix, move output to after header setting.

Quick Answer: Move output to after header setting or use output buffering to delay sending output.

📋 Table of Contents

⚠️ Common Causes
✅ Best Solutions to Fix It
🎯 Final Words

The 'Headers already sent' error in PHP occurs when you try to send HTTP headers after some output has already been sent to the browser. This can happen due to various reasons, including echoing or printing anything before sending headers.

This error is frustrating because it prevents your script from functioning correctly and may cause unexpected behavior. In this guide, we will walk through the root causes of this issue and provide two primary methods for fixing it.

⚠️ Common Causes

The primary reason for the 'Headers already sent' error is that you have sent output to the browser before sending HTTP headers. This can be due to echoing or printing anything before the header function calls, such as using echo or print statements before calling header().
Another possible cause is using output buffering functions like ob_start() and ob_end_flush() without disabling output buffering with ob_end_clean() or ob_get_clean() between the start and end of your script. This can also lead to sending headers after output has already been sent.

✅ Best Solutions to Fix It

Disable Output Buffering

Step 1: To fix this issue, you need to disable any output buffering that may be enabled in your PHP configuration. You can do this by adding ob_start() and ob_end_clean() around the section of your script where you are sending headers.
Step 2: Make sure to add ob_start() before any output is sent and ob_end_clean() after all headers have been sent. This will ensure that no output is buffered and that headers are sent correctly.
Step 3: You can also use ob_get_clean() to get the current buffer content and then clear it with ob_end_clean().

Check for Output Before Header Calls

Step 1: Another way to fix this issue is to check if any output has been sent before calling header(). You can do this by using the output buffering functions or by checking if ob_start() has been called.
Step 2: If you are using echo or print statements before your header calls, move them after the header function calls. This will ensure that no output is sent before headers are sent.
Step 3: You can also use a workaround like storing the output in a variable and then sending it after all headers have been sent.

🎯 Final Words

To summarize, the 'Headers already sent' error occurs when you try to send HTTP headers after some output has already been sent to the browser. By disabling output buffering or checking for output before header calls, you can fix this issue and ensure that your PHP script functions correctly.

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