Most of them still work. Old /main/... URLs automatically redirect to the corresponding pages in V5. For example, /main/dashBoard redirects to Dashboard, /main/userbasic redirects to Personal Profile Settings, /main/companybasic redirects to Company Profile Settings, and /main/po/item/{document ID} redirects to that PO page. Several old account and permission-related URLs also redirect to the corresponding tabs in "Account and Permission Management".
Exception: The old login URL /logon does not redirect on desktop version; use /login instead (for example, https://your-subdomain.patisco.com/login). Opening /logon on mobile will redirect to the mobile login page.
It is recommended that you update your bookmarks to the new URLs to avoid encountering missing pages in the future.