We are aware of that some times shoppers will receive a "Not Allowed! Sorry! You have no permission to view this page" error when browsing product detail pages or the cart in SC/A. Please raise a case for mitigation steps, and there is an active issue being tracked.

Just thought I would comment and add that we encountered this issue, but it was limited to a specific Chrome profile. Did not affect other browsers or profiles. Deleting all site data/cache/cookies resolved it.