So in case you get

err.type === Session.Error.TRY_REFRESH_TOKEN

, what will you do in there? Show a generic something went wrong error? Also, if you do send back

return { props: { fromSupertokens: 'needs-refresh' } }

to the frontend, the frontend will attempt to manually refresh the session which will call your API (not nextjs backend). So in a way, nextjs is not actually doing the refreshing.. it's just telling the frontend to refresh and then reload the page.