Tu n’es pas à l’abri d’un:

 Warning: Cannot modify header information - headers already sent by (output started at ...) in ...\pluggable.php on line 1210

Pour corriger contourner ça:

https://stackoverflow.com/questions/7381661/cannot-modify-header-information-headers-already-sent-by-wordpress-issue

our theme is printing output (text) to the browser, but then for some reason WordPress is redirecting the user (with wp_redirect) away from that page before the whole page is rendered. You can’t start printing output and then redirect, or you’ll get the error you see. That’s what Paul Grime was getting at in his comment.
Ken White commented with a reference to a post with a similar problem. I’ve fixed this in my own experience by buffering the output of the script.
In your theme’s functions.php file (which gets included every time your theme’s pages load), put the following:

//allow redirection, even if my theme starts to send output to the browser
 add_action('init', 'do_output_buffer');
 function do_output_buffer() {
 ob_start();
 }

Now, even if part of your theme starts to send input to the browser, PHP won’t send that text until the page is fully loaded, which allows WordPress to redirect users, if necessary, as part of its own logic.

=> Mon function.php