I have an app that copies a text file from a PC (running windows 7 or 10) to the same folder as the app is. Under Jesse it works perfectly. However in Buster it does not come over. Permissions appear to be 777 (in Rasparian they are Anyone, Anyone, Anyone). The data is transferred using UDP. I wrote both ends; I actually used auto discovery as the basis for the two ends that communicate.
Both ends work perfectly when the Pi is on Jesse, but the file never appears on pi when it is run under Buster. Any ideas why this would have become a problem? All of the other apps that are used in this environment work perfectly on both OS versions.