Looks like 4.3 nighties are synced as normal.
I don’t have any background knowledge about this, but the error message seems to indicate an invalid format with the `main` Alertmanager resource.
Someone should probably look at the CRD of Alertmanager and verify the `main` Alertmanager resource matches the CRD and is in latest version.
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-2020:0062