Common causes and solutions for header jump failure: 1. You can only use the header before outputting content. If there is space or output content at the beginning of the file, it will cause failure. The solution is to ensure that there is no output before the header or buffer it with ob_start; 2. Header parameters such as URL path or syntax errors will affect the jump. It is recommended to add exit immediately to terminate the subsequent code after writing the jump; 3. Browser cache may cause old data interference, so you should clear the cache or change the browser to test, and check the 302 response and Location header in the network request; 4. PHP configuration may hide error prompts, and you can temporarily turn on the error display to view "headers already sent" and other warnings. The troubleshooting sequence should first check the output problem, then confirm the correctness of the path, and finally eliminate other interfering factors.

Sometimes I want to jump to the page using PHP header('Location: ...') , but I don't respond or even report an error. This problem is actually quite common, and there are several main reasons, let’s take a look at it one by one.

Only use header before outputting content

The header() function of PHP must be called before any actual output, including HTML, spaces, line breaks, etc. As long as the browser receives a little content, the header cannot send it normally.

Common Situations:

• A space was accidentally added after the file has <?php
• Use echo , print , or write HTML content directly
• The included files have output (such as config.php)

Solution:

• Make sure there is no output before header() is called
• You can enable ob_start() to buffer output and delay sending content
• Use headers_sent() to determine whether the over-head information has been sent

The header() parameter is written incorrectly

Although it seems simple, incorrect parameter writing can also cause the jump to fail to take effect. The most commonly used formats are:

 header('Location: /path/to/page.php');

Prone to errors:

• The URL is written incorrectly, such as the path is incorrect or the spelling is incorrect
• Forgot to add quotes or brackets, resulting in syntax errors
• Without exit() or die() , the program continues to execute the following content

It is recommended to add exit; immediately after writing and jumping to avoid interference from subsequent code:

 header('Location: login.php');
exit;

Browser caching or redirection issues

Sometimes you change the code, but the browser is still using the old cache, which may make you mistakenly think that the jump is not effective.

You can try:

• Clear browser cache or change browser test
• Check the network request panel to see if there are 302 responses and correct Location headers
• If redirected using .htaccess or server configuration, conflicts may also occur

PHP configuration restrictions or warnings are hidden

Some server environments have restrictions on header, or the error message is closed, causing you to not see the specific problem.

You can temporarily open the error prompt to see if there is any warning:

 ini_set('display_errors', 1);
error_reporting(E_ALL);

In this way, if there is an error like "headers already sent", you can see the prompt.

Basically these common reasons. When encountering header location not working , first check whether there is any output in advance, then confirm whether the jump path is correct, and finally see if there are other interfering factors. The troubleshooting order is roughly based on this, and you can usually find the problem.

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