MySQL 5.6 Reference Manual Including MySQL NDB Cluster 7.3-7.4 Reference Guide

17.4.1.14 Replication and Fractional Seconds Support

MySQL 5.6.4 and up permits fractional seconds for TIME, DATETIME, and TIMESTAMP values, with up to microseconds (6 digits) precision. See Section 11.2.7, “Fractional Seconds in Time Values”.

There may be problems replicating from a source server that understands fractional seconds to an older replica that does not: