UPDATE, 08/10/17, 9:13 AM:
Canvas engineers have implemented a fix allowing users to access Canvas. Users are now able to log in. For details, visit http://status.instructure.com/.
If you continue to see the error message that was displaying during the outage, please try clearing your browser cache and history, quitting your browser application, and then re-opening it.
ORIGINAL MESSAGE, 08/10/17, 9:00 AM