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LTI 1.3 "sub" not the same as 1.1 "user_id"?

Question asked by Jack Borrebach on Oct 4, 2019
Latest reply on Oct 17, 2019 by Jack Borrebach

My team is working on our LTI 1.3 tool implementation.

I’ve been running some test scenarios where our LTI tool is “upgraded”. That is, I launch an LTI link in a test course using a 1.1 tool, then replace that tool with a 1.3 tool associated with the same domain, and launch that same link again.


I think I’m seeing that the “sub” claim in the LTI 1.3 launch doesn’t match the “user_id” parameter in the LTI 1.1 launch. With the other platforms we're integrating with, these terms are the same.

  • LTI 1.1 user_id: 5b57828bb93b88119cc48a4c5070d3207d69366e

  • LTI 1.3 sub, for same user: 7bb30dfe-bfd8-4872-86c1-3e50718e9f51 


Am I observing this accurately, and if so, is this the expected behavior? I know the IMS specs describe the possibility of it.


And if so, then do you have a recommendation for how we could obtain the user’s “old” user_id in a 1.3 launch?


I believe I’m also seeing a different resource link ID for the same assignment. We don’t actually use that info in our system, so that doesn’t matter to us though.