How can the "Cannot modify header information" error be resolved in PHP when using header() function?

The "Cannot modify header information" error in PHP occurs when there is output sent to the browser before calling the header() function to set HTTP headers. To resolve this issue, make sure that there is no output (such as whitespace or HTML) before calling the header() function. You can use ob_start() and ob_end_flush() functions to buffer the output and prevent this error. 

<?php
ob_start();
// Place your PHP code here

// Example of setting a header after buffering output
header("Location: https://www.example.com");
ob_end_flush();
?>

Keywords

header function Cannot modify header information output buffering ob_start ob_end_flush

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