The Error Message:
500 JWT signature does not match locally computed signature.
This is usually not a problem with your computer hardware or internet connection. It is likely caused by one of the following:
Stale Session: Your login session expired in the background, but your browser is still trying to use the old "ID badge" (token).
Server Update: The school's system (or the specific test provider) may have restarted or updated its security keys while you were logged in, effectively invalidating everyone's current tokens.
Browser Caching: Your browser is holding onto an old piece of data that contradicts what the server expects.
Please try these steps in order, from easiest to most thorough:
Log Out and Log Back In (Most Likely Fix)
Manually log out of your session
Close your browser tab.
Open a new tab, go back to the site, and log in again. This forces the server to generate a brand new, valid JWT for you.
Try Incognito/Private Mode
Open a "New Incognito Window" (Chrome) or "Private Window" (Firefox/Edge).
Log into the LMS and try to access the material again.
Why this helps: Incognito mode does not use your saved cookies or cache. If it works here, the problem is definitely a stuck cookie in your main browser.
Clear Browser Cache and Cookies
If Incognito mode worked, you need to clear your cache to fix your main browser.
Go to Chrome Settings > Privacy and security > Clear browsing data.
Select "Cookies and other site data" and "Cached images and files."
Contact Support - click here
If the steps above do not work, the issue is on the school's end (server-side).
You will need to provide them with the Reference Code shown in your error message (example: LTG-XGWK2L3S-20251216.130926)