I am setting up LTI integration with Canvas. Everything is working fine except getting this error - "Your score was not successfully sent to the LMS". The error appears randomly from time to time. The grades are updated in LTI when there is no error.
I set $LTIGradeOnSubmit = 1; to update the grades as soon as students answer the questions.
Warning messages
Unable to update LMS grade. Error: Unauthorized at /opt/webwork/webwork2/lib/WeBWorK/Authen/LTIAdvanced/SubmitGrade.pm line 283.
This is the Error log from Apache
[/webwork2/Maths_Linna/Angles_homework/19/] Unable to update LMS grade. Error: Unauthorized at /opt/webwork/webwork2/lib/WeBWorK/Authen/LTIAdvanced/SubmitGrade.pm line 283., referer: https://webwork.school.edu/webwork2/Maths_Linna/Angles_homework/19/
Could anyone help what's wrong with this? Thanks.