This is a common error on Canvas:
To fix it:
If you're having problems logging in, try these steps:
Go to the crimson app (app.crimsoneducation.org)
Logout
Open Canvas again (lms.cga.school)
Login with your CGA email
If this still doesn't work, please try clearing your browsing data.
Instructions are here.
If the above steps don't work, please reach out to mycga@cga.school for help.