After upgrade to 2.3.0 and installing module newsletter-v0.1 SilverStripe is working but Newsletter not. in PHP-Errors:
PHP Fatal error: Class 'ProgressBar' not found in /home/silvers/wirt/site/newsletter/code/NewsletterAdmin.php on line 448
After commenting out references to the missing ProgressBar it starts - but is not usable at all. No respond for creating a new mail.