I have an Android app which does, among other things, FTP uploads and downloads with a file server. Up to Android 10, all is fine, but I'm getting problems with Android 11.

I have opened a FileStream. Available shows the right byte count, and a read returns a byte array with the right data in it, so my Android/Java app can handle it fine. A FTPSClient storeFile creates a file on the server, but the data is totally corrupt. The application also locks, the storeFile never returns until I am forced off the server. It's all in a try/catch, with enough catches to choke an elephant. All files are in a folder within my application 'sandbox'. As I said, my Java code can handle the file.