Satellite upgrade fails with error "Unable to detect features"

Issue

• Red Hat Satellite upgrade from 6.10 to 6.11 failed to refresh the features of the internal smart-proxy in the step:

  # satellite-maintain upgrade run --target-version 6.11 --whitelist="check-tmout-variable,non-rh-packages,check-hotfix-installed"
  

• When previous command is running, the following error can be observed in terminal and /var/log/foreman-installer/satellite.log:

  | Executing installer2023-05-10 09:50:51 [ERROR ] [configure] /Stage[main]/Foreman_proxy::Register/Foreman_smartproxy[satellite.example.com]: Failed to call refresh: Error making PUT request to https://satellite.example.com/api/v2/smart_proxies/1/refresh: Unable to communicate with the Capsule: ERF12-2530 [ProxyAPI::ProxyException]: Unable to detect features ([RestClient::Exceptions::ReadTimeout]: Timed out reading data from server) for Capsule https://satellite.example.com:9090/v2/features Please check the Capsule is configured and running on the host. Unable to communicate with the Capsule: ERF12-2530 [ProxyAPI::ProxyException]: Unable to detect features ([RestClient::Exceptions::ReadTimeout]: Timed out reading data from server) for Capsule https://satellite.example.com:9090/v2/features Please check the Capsule is configured and running on the host.
  

• The upgrade was interrupted and Red Hat Satellite services are not able to start correctly.