Hi there, I posted about my task about uploading files here https://developer.apple.com/forums/thread/808756 and am also getting unpredictable expirations, especially on cellular connections. One thing I noticed is that when I tried to use the child progress, the fractionCompleted updates, but the completedUnitCount does not until the chunk is done. I wonder if expiration happens by looking at completedUnitCount and not fractionCompleted? If not, any other ideas as to why my UploadTask on cellular is getting killed much more frequently than on wifi? I fixed some issues on wifi where I noticed if the CPU usage is too high it gets killed, but I've since fixed those, and wifi is pretty stable, but cellular is very unstable.

Update: I just tried replacing the child progress with a UrlSessionDelegate that updates the progress completedUnitCount directly, and it seems to be more stable (but I only tried this once) Potentially a bug with using Child Progresses to keep alive BGContinuedProcessingTasks?

Ah interesting, Based off that, it feels like I should NOT rely on the BGContinuedProcessingTask notifications (or whatever they are called) to communicate state. It seems like instead what I should do is do something like local notifications to communicate state and handle it more in my app, is that correct?

I forgot to mention I am using multipart upload, and so completedUnitCount gets updated on each Chunk. I could reduce the chunkSize, but ideally would still prefer to just have it be kept alive by fractionCompleted (if that is indeed the issue)

Here is the bug number FB21338185 The test file I am testing with is 7 GB, and on cellular the upload can be a bit slow. I can test again, but I think in case 1, the progress updater updates much more slowly than it does when directly updating the progress task in case 2. Perhaps the UI only looks at completedUnitCount and not fractionCompleted as well? If it's interesting I can see if I can try to repro it more clearly

Thank you! here is the bug number FB21338204