My organization is in the process of upgrading our ArcGIS server to 10.4.1 along with Arc Desktop, Catalog, etc. We use ArcGIS viewer for Flex for all internal applications. I read the list of deprecated features for Arc 10.3 and 10.4 and saw that the Flex Viewer was one of them. I understand that Flex hasn't received support or an update since 2014/15. My question is, if we upgrade our software to 10.4.1, will the Flex viewer simply not work anymore? These applications are crucial to daily tasks and I do not want them to stop working once we upgrade to 10.4.1. I am in the process of putting our GIS applications in the Javascript API but with all of the different applications we use, it will take a long time. Any help is greatly appreciated!

My organization is in the process of upgrading our ArcGIS server to 10.4.1 along with Arc Desktop, Catalog, etc. We use ArcGIS viewer for Flex for all internal applications. I read the list of deprecated features for Arc 10.3 and 10.4 and saw that the Flex Viewer was one of them. I understand that Flex hasn't received support or an update since 2014/15. My question is, if we upgrade our software to 10.4.1, will the Flex viewer simply not work anymore? These applications are crucial to daily tasks and I do not want them to stop working once we upgrade to 10.4.1. I am in the process of putting our GIS applications in the Javascript API but with all of the different applications we use, it will take a long time.