Is it possible to determine the version of an app a user is using ? and if so ? require their browser / device to sync the app like a fresh start or relaunch. It is not an option to ask users all over the world to clear their device /browser cache.
here is the logic:
new app version 10.1 is current and live
old app version 9.9 is cached in users device or browser
have a valid_if / context(???) that checks version number and report an error to user
“your version 9.9 is not the lastest version” please restart your app / clear browse /device cache etc