in Personal settings, one can configure to open the dashboard with "Previous 7 days" default dates. For such choices, some widgets in the dashboard are not working and an error message is displayed instead of the graph: " Date format must be: YYYY-MM-DD, or 'today' or 'yesterday' or any keyword supported by the strtotime function (see http://php.net/strtotime for more information): 2017-11-26,previous7 "

-> the issue is that widgets receive the date=2017-11-27,previous7 parameter instead of just previous7

Reproducible at such URLs: index.php?module=CoreHome&action=index&idSite=1&period=range&date=previous7#?idSite=1&period=range&date=previous7&category=Dashboard_Dashboard&subcategory=1

Many other widgets affected as well