The Content Manager Explorer user interface in SDL Web 8.5 has changed a number of prerequisites compared to SDL Tridion 2013 SP1 HR1 or SDL Web 8 with Cumulative Update 1 applied.
Content Manager Explorer operating system support history Prior to SDL Web 8.5, the product included an explicit list of operating systems that supported the Content Manager Explorer user interface. Starting from SDL Web 8.5, operating system support is instead a blanket statement of support for all desktop operating systems that support any of the supported internet browsers.
Changing browser response to unsupported version If you want, you can change how Content Manager Explorer responds to a specific browser version after your installation, you need to configure the system.config file.