LTI Launch error when trying to launch

[YuvalYellin]

We are developing an LTI tool that already works well in Canvas in production in an institution and in out own env (https://exlibris.instructure.com/ ) 

We are now trying to integrate with a Test instance of another institution, and we are getting this Launch Error screen. 

My setup of the LTI side is as followed: 

"accesstokenEndpoint": "https:///sso.test.canvaslms.com/login/oauth2/token",

"authConfig": {

"method": "JWK_SET",

"key": "https:///sso.test.canvaslms.com/api/lti/security/jwks"

},

"authEndpoint":"https:///sso.test.canvaslms.com/api/lti/authorize_redirect",

"clientId": ...

"url": "https://canvas.test.instructure.com"

Hpwever, unlike our own production instance, the authorize_redirect doesn't seem to work as expected - in the production instance , when doing an authorizd_redirect request we are then redirected to the production instance url  ( https://[our instauction url/api/lti/authorize?..  ) and everything works. 

In the test Canvas instance we are now using, we are instead redirected to 

https://calstatela.test.instructure.com/api/lti/authorize?..., and then getting the launch error. 

Is there something wrong with the setup? should we use another url ? How can we know what's the real issue here? 

[matthew_buckett]

I'm not sure if this is the problem but in your configuration lots of the URLs have an extra '/' in them in between the protocol and host. eg:

https:///sso.test.canvaslms.com/login/oauth2/token

should be:

https://sso.test.canvaslms.com/login/oauth2/token

If you fix that does it get further?

[YuvalYellin]

I actually didn't have the extea '/' in my setup, just an artifact of my editing this. 

What did work for me is using this setup (whithout the sso endpoint but using the previous way of working with real URLs of the canvas instance) :

"accesstokenEndpoint": "https://exlibris.test.canvaslms.com/login/oauth2/token",

"authConfig": {

"method": "JWK_SET",

"key": "https://exlibris.test.canvaslms.com/api/lti/security/jwks"

},

"authEndpoint":"https://exlibris.test.canvaslms.com/api/lti/authorize_redirect",

"clientId": ...

"url": "https://canvas.test.instructure.com"

That is . using the real URLs of the test environment instead of the recommended sso value. In the prod instance, the sso URL worked fine, so I am not sure whether it's a bug or an error in the documentation.