We've been using LTI to integrate a 3rd party assessment tool with our moodle. The 3rd party app is launched via a link on the course page, when complete a grade is sent back to moodle and stored in the grade book. This has been working preferably until a week ago.
The app still launches but the grades do not update. The error "Message signature not valid" is returned.
When trying the test tool http://lti.tools/test/tp.php , the grade doesn't return . We just get an error.
This suddenly stopped working last Monday. The assessment developer has not changed anything. The moodle host says the server and ip changed but nothing else.
Any suggestions?