admin-ajax return error 400 for Chrome/Edge but not Firefox

Problem fixed !
The problem was not due to a browser matter.
wp_ajax_nopriv_myfunction was wrapped by is_admin(). That could not work.
I was logged in in Firefox and not in Chrome that´s why I thought it was a browser matter.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)