Sorry about that. Are you able to log in using a different browser, such as Chrome, and can you log in when visiting this URL https://lastpass.com/?ac=1&lpnorefresh=1 or is the same issue happening as well in a different browser?
Thanks for keeping us updated. This looks to be a bug our team would like to get more specific information about. So that our team can gather more details, could you submit a bug report following these steps? https://support.logmeininc.com/lastpass/help/how-do-i-report-a-bug-to-lastpass