Title: Warning: Cannot modify header information – headers
Last modified: November 8, 2025

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# Warning: Cannot modify header information – headers

 *  [druideniggi](https://wordpress.org/support/users/druideniggi/)
 * (@druideniggi)
 * [5 months, 4 weeks ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-headers/)
 * Hello everyone, I have the following note in the debug:
 * **Warning**: Cannot modify header information – headers already sent by (output
   started at r/wp-content/plugins/back-in-stock-notifier-for-woocommerce/includes/
   vendor/MobileDetect.php:1232) in **//wp-includes/pluggable.php** on line **1108**
 * Twenty Twenty-Five Version: 1.3
 * All plugins updated, PHP Version 8.4
 * Does anyone know the problem?

Viewing 1 replies (of 1 total)

 *  [guenther999](https://wordpress.org/support/users/guenther999/)
 * (@guenther999)
 * [5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-headers/#post-18737655)
 * Hello,
 * I have also the same problem with Divi theme:
 * Deprecated: CWG_Detection\MobileDetect::isTablet(): Implicitly marking parameter
   $httpHeaders as nullable is deprecated, the explicit nullable type must be used
   instead in /wp-content/plugins/back-in-stock-notifier-for-woocommerce/includes/
   vendor/MobileDetect.php on line 1232

Viewing 1 replies (of 1 total)

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 * 1 reply
 * 2 participants
 * Last reply from: [guenther999](https://wordpress.org/support/users/guenther999/)
 * Last activity: [5 months ago](https://wordpress.org/support/topic/warning-cannot-modify-header-information-headers/#post-18737655)
 * Status: not resolved