A method and associated computer system. A processor queries a service catalog and a virtual service inventory to obtain network service instances including a virtual network function. The processor seamlessly replaces the virtual network function by a new version of the virtual network function without interruption of the network service in the production environment. The processor deploys the new version of the virtual network function unattached to the production environment, including: replacing a network address of the virtual network function in the load balancer with a network address of the new version of the virtual network function. In response to a determination by the processor that the virtual network function has a floating network address, the processor detaches the floating network address from the virtual network function and attaches the detached floating network address to the new version of the virtual network function.