Why Sending a 404 Error in PHP May Not Work
In PHP, if you encounter an empty page despite using code to set a 404 Not Found header, it's because:
if (strstr($_SERVER['REQUEST_URI'],'index.php')) {
header('HTTP/1.0 404 Not Found');
}
While technically correct, this code lacks a crucial step: PHP is responsible for outputting the 404 error page.
How 404s are Typically Handled
Normally, 404 errors are managed by the web server:
- User requests a URI.
- Webserver checks for the file at that URI.
- If the file is not found, the webserver sends a 404 header and displays a 404 error page.
PHP's Role in Error Handling
However, when a PHP page is executed, the webserver passes control to PHP before it can handle a 404.
- User requests a URI.
- Webserver detects a PHP page and passes control to PHP.
- PHP checks for the file and discovers it's not found.
- PHP sends a 404 header but now becomes responsible for displaying the error page.
In this scenario, PHP lacks the capability to show a custom 404 page, resulting in a blank page. To resolve this issue, you can incorporate your desired 404 page within the PHP code or redirect to a dedicated 404 page that exists outside of the PHP application.
The above is the detailed content of Why Does My PHP 404 Header Result in a Blank Page?. For more information, please follow other related articles on the PHP Chinese website!
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