En sélectionnant dans Menu/commentaires,  j'obtiens ces deux messages en haut de l'image:

Notice: Undefined index: QUERY_STRING in E:\Piwigo_dossier\PiwigoPortable_2.2.3-fr-r01.fmk\PiwigoPortable\App\piwigo\include\functions.inc.php on line 660

Warning: Cannot modify header information - headers already sent by (output started at E:\Piwigo_dossier\PiwigoPortable_2.2.3-fr-r01.fmk\PiwigoPortable\App\piwigo\include\functions.inc.php:660) in E:\Piwigo_dossier\PiwigoPortable_2.2.3-fr-r01.fmk\PiwigoPortable\App\piwigo\include\page_header.php on line 98

A noter aucun plugin installé...

Cordialement, Laurent