Once installed, you’ll find it at: \Steam\steamapps\common\Skyrim Special Edition\Data\Skyrim.esm

: If verification fails, the most reliable way to restore core master files is a clean uninstallation followed by a fresh reinstall through your official game store.

Here’s why:

Every single mod you’ve ever installed—from SkyUI to Legacy of the Dragonborn —overrides or adds to records inside Skyrim.esm . It’s the baseline.

Select the menu (next to 'Play') > Manage installation > Verify / Repair .