Sony has rolled out an unexpected update to Xperia C4 and C5 Ultra smartphones. These phones received the last update back in January 2018. The new update brings 5 March 2018 Android security patches to both the smartphones. Sony Xperia C4 update changes the build number to 27.3.A.0.173 and the dual-SIM version build number moved to 27.3.B.0.173. Sony Xperia C5 Ultra build number changes to 29.2.A.0.174 and the dual SIM variant build number moves to gets 29.2.B.0.174.