SERVER-26117 made it so that if initial sync encounters a renameCollection it will fail and restart, rather than proceeding and potentially corrupting data as it did in previous versions. Taht change is present starting in 3.2.12 and 3.4.0. We should make clear in the release notes for both that upgrading from 3.2.11- may cause initial syncs to start failing, especially if you are regularly using renameCollection or aggregation or mapReduce with $out (which performs a renameCollection internally)