Start with the window and full error, not just the launcher label. Keep protection enabled. Rendering arguments must match the cited current Epic guide, and the original text and toggle should be saved before changing them.
Sources
We checked these official pages and wrote the steps in our own words. Follow the publisher’s page if it has changed.
Epic: Fortnite shows running but does not openEpic: verify game filesEpic: install Easy Anti-Cheat for FortniteEpic: Fortnite graphics and Performance Mode Japanese version of this page