If after registering Labster with your Moodle, you or the students receive this error message:
This has been identified as a server/firewall configuration on the school side that removes headers from incoming requests (more specifically the Authorization header). LTI 1.3 protocol requires these headers as a part of the authorization and it is mandatory.
You can take a look at how to resolve it here: https://moodle.org/mod/forum/discuss.php?d=389429#p1597517
Please do not hesitate to reach out to our support team if you have any questions or are in need of assistance.