Empirical Core is the mono repo for the Quill.org codebase. This repo contains both the Quill Learning Tools, such as Quill Connect, and the Quill Learning Management System, the platform that enables teachers to provide assignments and view results. (Empirical is the name of the nonprofit building Quill.org).
Users going to this URL: http://www.quill.org/about
The about page got deleted in this PR: https://github.com/empirical-org/Empirical-Core/pull/605
Suggested fix is to redirect that to /mission
More info on Sentry: https://app.getsentry.com/empirical-core/production/group/31311752/