@panosakris, temporary fix was just to back up the offending script and save it as an empty file:
/wp-content/plugins/stops-core-theme-and-plugin-updates/templates/notices/thanks-for-using-main-dash.php
cp thanks-for-using-main-dash.php thanks-for-using-main-dash.php.bak && echo "" > thanks-for-using-main-dash.php
The dashboard and plugin configuration page works as expected for me afterwards.