A server system including an application server system that provides a service according to a request from a web browser included in a terminal , the server system configured to change the application server system from a first application server system to a second application server system, the server system comprising: deployment means configured to deploy (S603) a plurality of modules for implementing the service in the second application server system, the plurality of modules having a configuration different at least in part from that of a plurality of modules for implementing the service, deployed in the first application server system; storage means configured to store (S604) a first resource corresponding to the plurality of modules deployed in the first application server system and a second resource corresponding to the plurality of modules deployed in the second application server system, the first and second resources being resources required to display a screen to be displayed by the web browser ; and switching means configured to switch (S605) a source of the service from the first application server system to the second application server system after deployment is performed by the deployment means , wherein, after switching by the switching means, the first application server system is excluded from components of the server system, and the first resource is deleted from the storage means , wherein, after switching by the switching means , if a request regarding display of the screen is accepted from the web browser and data included in the request is confirmed to be associated with the first resource, the second application server system is configured to obtain (S710) the first resource from the storage means and transmit (S712) the first resource to the web browser in a case where the first resource has been stored in the storage means, and to generate an error response and transmit (S803) the generated error response to the web browser in a case where the first resource has not been stored in the storage means . deployment means configured to deploy (S603) a plurality of modules for implementing the service in the second application server system, the plurality of modules having a configuration different at least in part from that of a plurality of modules for implementing the service, deployed in the first application server system; storage means configured to store (S604) a first resource corresponding to the plurality of modules deployed in the first application server system and a second resource corresponding to the plurality of modules deployed in the second application server system, the first and second resources being resources required to display a screen to be displayed by the web browser ; and switching means configured to switch (S605) a source of the service from the first application server system to the second application server system after deployment is performed by the deployment means , wherein, after switching by the switching means, the first application server system is excluded from components of the server system, and the first resource is deleted from the storage means , wherein, after switching by the switching means , if a request regarding display of the screen is accepted from the web browser and data included in the request is confirmed to be associated with the first resource, the second application server system is configured to obtain (S710) the first resource from the storage means and transmit (S712) the first resource to the web browser in a case where the first resource has been stored in the storage means, and to generate an error response and transmit (S803) the generated error response to the web browser in a case where the first resource has not been stored in the storage means . <EOS>