I am curious if any other tool providers have started experiencing this issue. We first became aware of it several days ago (4/6/19). Whenever our LTI tool attempts to report to Canvas, we receive the following error:
400 The plain HTTP request was sent to HTTPS port
This is the first time I've encountered this error with our tool in two years. It was working two weeks ago, and we have not updated anything since then. All requests to and from Canvas are over HTTPS as well, which is why this is extra confusing. We have verified that the tool continues to work with other LTI tool consumers.
If anyone has an insight, it would be greatly appreciated. Thank you.