We are aware that https://data.tfl.gov.uk/tfl/syndication/feeds/TubeThisWeekend_v2.xml is currently broken due to a Varnish issue. You can continue to access this feed at this URL while we work to fix the Varnish error: https://tfl.gov.uk/tfl/syndication/feeds/TubeThisWeekend_v2.xml
NB: We will be turning off the data.tfl.gov.uk domain on 18th April so if you use any feeds at this url you should be in the process of migrating these to tfl.gov.uk anyway. See also - Deprecation of data.tfl.gov.uk domain for legacy feeds