Canvas is performing emergency maintenance.
Canvas provided the following details:
DevOps team has identified an issue with your instance of Canvas that is
resulting in slowness and page errors for your users when they attempt to
create new objects in their courses (uploading files, creating new assignments,
etc). They have been able to alleviate some of these problems with temporary
fixes throughout the morning, but it is at a point they will need to perform an
emergency maintenance to fully fix the issue.
We'll be performing a brief emergency maintenance event on your Canvas instance today (July 24th) at 9:30 AM MDT. This event can last up to 10 minutes, though we are expecting less. Your users will not be able to access Canvas while the event is underway."