Most Tube station ticket machines are only accepting bank cards. You can top up using your contactless and Oyster account, the TfL Oyster and contactless app or an Oyster ticket stop. Ticket machines at all London Overground and DLR stations are still accepting cash.
London Overground: No service between Highbury & Islington and Clapham Junction / New Cross / West Croydon / Crystal Palace and between Liverpool Street and Enfield Town / Cheshunt / Chingford due to planned works. A reduced service is operating on other London Overground routes due to operational restrictions.