The circumstances that have prevented Tyler, The Creator from playing the Reading and Leeds festivals this weekend have been explained as visa issues. His manager, Christian Clancy, took to Tumblr to say ""Tyler has been banned from entering the UK for somewhere between three to five years per a letter from the Secretary Of State for the home department [sic] of the United Kingdom. The letter specifically cites lyrics he wrote six to seven years ago for his albums 'Bastard' and 'Goblin' the type of lyrics he hasn't written since... highlights from the letter include that his work 'encourages violence and intolerance of homosexuality' and 'fosters hatred with views that seek to provoke others to terrorist acts'. I grew up on NWA, Eminem and Rage Against The Machine, so it's hard for me to fully wrap my head [around] this thought process and its implications". The rapper also recently cancelled dates in Australia, where there had been calls for his visa application to be denied because of similar issues with past lyrics.
More here http://www.theguardian.com/music/musicblog/2015/sep/01/tyler-the-creator-comments-banned-uk-freedom-of-speech