1. cluster admin visit Administration -> Cluster Settings page
2. check Channel list, prerelease-4.2 is in the list
It has been fix in 4.1.0-0.nightly-2019-10-08-233046, will double confirm on 4.1.19
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2019:3004