SPICE HTML5 support has now been removed. This was previously a Tech Preview feature. Support should be removed from the Admin Guide[1] and possibly elsewhere. [1] https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2-beta/html-single/administration_guide/#sect-Websocket_Proxy
Updated documents: https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2-beta/html-single/administration_guide/#SPICE_Proxy_Overview https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2-beta/html-single/administration_guide/#Websocket_Proxy_Overview https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2-beta/html-single/installation_guide/#appe-Installing_the_Websocket_Proxy_on_a_different_host https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2-beta/html-single/planning_and_prerequisites_guide/#RHV-manager-firewall-requirements https://access.redhat.com/documentation/en-us/red_hat_virtualization/4.2-beta/html-single/planning_and_prerequisites_guide/#client-requirements