I have created a set of LTI inks on one Moodle site, at a course level and used them to establish links on another Moodle site. After adding the URL and the secret I get a tick and a message saying Using tool cartridge. Then I save it and I get this error.
Error reading file "http://landbasedlearningltd.com/enrol/lti/cartridge.php/1369/e86e34a9f82948f2c654088d96a815d7/cartridge.xml"
Interestingly I have already added this same link on the same course, on another external link and it works fine. If however when I make a duplicate of the external resource link the link fails to work. It links to the site but gives this error.
A required parameter (oauth_consumer_key) was missing.
In fact, I can not get any other link to work on this site. Why do I get this error?
Another interesting point is that on another Moodle test site I operate I have used the same URL to establish a number of different external links and they all work perfectly.
Has anyone got any ideas about this?
Found my own solution, may be obvious to you professional but thought I would share it.
There appears to be a huge inconsistency in the way that the different LTI links work, on the different versions of Moodle. Some versions of Moodle, will accept the links as we created them in Moodle 3.3.1 as the cartridge Plugin. We have discovered that some versions of Moodle will not accept these cartridge links and they will only accept a more basic link, based on a simple URL
So if the cartridge link, fails then to manually add the enrolement url and secret. If you do use this method you must open the 'see more' link and add a word to the consumer key. Without this key, the link will not work.
Hope this helps.