Downgrade win 10 1803 to 1709 in Windows 10 Posted July 1, 2018 · Report reply I have a 16 bit windows app that works absolutely fine on win 10, 1709. Since I upgraded to 1803, that app no longer works on it. The app is an old Delrina app called Perform. Perform is very important to me but I have not found any app that works as well to create and use forms. The closest app that does work is FORMDOCS. Formdocs will come close to converting Perfom files to Formdocs. The problem with Formdocs is that you have to run the Perform app first, then convert. In most cases, it is very hard to convert and eventually causes you to create a new file, which is not easy and efficient as the Perform app. As I said, Perform (16bit) runs perfectly on Windows 10, version 1709. Running compatibility mode on win 10 does not work for Perform, but DID work on version 1709, and very well. All I get now with 1803 is "can't run 16bit apps" and exits. Why? I can't even go back to installing version 1709. I thought this was an upgrade....to me, this is a downgrade. My business depends on this 16bit app called Perform.