So, after an exchange with Canvas support, the answer to my confusion is that Canvas does not allow a line item to exist without being associated with an assignment.  So when a line item request is re...

The solution for this proposed by IMS involves the $ResourceLink.id.history custom parameter substitution variable (see https://www.imsglobal.org/lti-course-copy-road-nowhere) but I don't think Ca...

The more I test the LTI LineItem service in Canvas, the more confused I seem to become.  I have already reported in a separate post about line items I create not being visible within the Canvas Gradeb...

The LTI Course Groups service is currently at the IMS Candidate Final stage.  Does anyone know whether Canvas plans to implement this specification and, if so, whether there is any expected timescale ...

With IMS deprecating the OAuth 1.0A authentication mechanism used by LTI 1.0/1.1/1.2/2.0 last year (certification ceased 1 July 2021, see https://www.imsglobal.org/deprecation-notice-oauth-10a), I was...

Yes, that looks like the cause.

Interesting; so it looks like it is a Ruby issue rather than an LTI one.  Ruby does not seem to recognise jwt_string as being a string on which it can apply the count method.  Sorry, I'm not a Rub...

On further review, it looks like your response may have the iss and aud claims the wrong way round; try switching them.

My only suggestion would be to send the "aud" claim as an array.  The Security Framework 1.1 spec is inconsistent on this matter: at one point it states that the claim MUST be an array (sectio...

If you're getting the same error with an empty array of content items, then try checking the JWT as a whole is properly formed (e.g. check headers).  Also try removing the sub and locale claims, a...