How to fix the issue ?
It’s just necessary to rebuild index :
root@my:~# /usr/bin/php /var/www/humhub/protected/yii search/rebuild
Rebuild search index: ..........OK !
root@my:~# /usr/bin/php /var/www/humhub/protected/yii queue/run
root@my:~# /usr/bin/php /var/www/humhub/protected/yii cron/run Frédéric.