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My Files shows library.errors.signInRequired when there is no member session.
Why this happens
Library listing is per-account. Related gates: Sign in required (Manage Account), Sign in to view deleted files.
Diagnose and fix
1. Sign in, then reopen My Files.
2. If the session expired mid-browse, sign in again and refresh.
3. See My Files library (browse, search, sort).
4. See Sign in to view live downloads / Sign in to view reports for other member pages.