How to resolve the issue of not being able to set up error page redirection in PHP.

In PHP, setting up error page redirection can be achieved by setting the HTTP status code and Location header. If error page redirection cannot be achieved, it may be because there is other content being output elsewhere in the code or other HTTP headers being set, preventing the Location header from being set. Some possible solutions to try include:

1. Make sure there is no output, including spaces or line breaks, before setting the Location header.
2. Make sure that no other places have set HTTP headers, such as using the header() function.
3. You can use the ob_start() function to activate output buffering, and then clear the buffer before setting the Location header.
4. One way to achieve page redirection is by using JavaScript, such as setting window.location.href to redirect to an error page.

If none of the above solutions work, you can try checking the PHP error log or server error log to see if there are any other error messages causing the inability to redirect. If the issue persists, it is recommended to further troubleshoot and debug the code.