Message d'erreur dans le header - par: 2WD63

J'ai ces deux messages dans l'entête et je ne comprends pas comment c'est venu ni pourquoi.

Warning: mysqli::mysqli(): Headers and client library minor version mismatch. Headers:50541 Library:50633 in /home/webdesign/public_html/intranet/core/db/mysqli.class.php on line 188

Warning: Cannot modify header information - headers already sent by (output started at /home/webdesign/public_html/intranet/core/db/mysqli.class.php:188) in /home/webdesign/public_html/intranet/main.inc.php on line 975...