Alertmanager 0.21.0 not supported?

level=info msg="Reading configuration file" path=/app/config.yml
level=info msg="Version: v0.111"
level=info msg="Configured Alertmanager source" name=test-cp proxy=true readonly=false uri=http://prometheus-alertmanager.monitoring.svc.cluster.local
level=info msg="Setting up proxy endpoints" alertmanager=test-cp
level=info msg="Initial Alertmanager collection"
level=info msg="Pulling latest alerts and silences from Alertmanager"
level=info msg="Collecting alerts and silences" alertmanager=test-cp
level=info msg="GET request" timeout=10 uri=http://prometheus-alertmanager.monitoring.svc.cluster.local/metrics
level=info msg="Upstream version" alertmanager=test-cp version=0.21.0
level=error msg="Collection failed" error="can't find status mapper for Alertmanager 0.21.0" alertmanager=test-cp try=1/2
level=info msg="GET request" timeout=10 uri=http://prometheus-alertmanager.monitoring.svc.cluster.local/metrics
level=info msg="Upstream version" alertmanager=test-cp version=0.21.0
level=error msg="Collection failed" error="can't find status mapper for Alertmanager 0.21.0" alertmanager=test-cp try=2/2
level=info msg="Collection completed"
level=info msg="Done, starting HTTP server"
level=info msg="Starting HTTP server" address=[::]:9094
level=info msg="Shutting down HTTP server"