I renamed the widget and restart mysql to recover forum.
But now I've many outofrangeexception errors in the log.
How can I remove widget without uninstall the plugin?
/home/xxxxxxxx/public_html/system/Dispatcher/Front.php(432): IPS\_Widget::load(Object(IPS\Plugin), 'topicThumbnail', 'lag1kyhl1', Array, NULL, 'vertical')