Assuming that the message was from the Core Data framework, the reason would be that Core Data was trying to extend the app's background execution time to do a write request by calling beginBackgroundTask(withName:expirationHandler:), and the API returned invalid, which means that the system didn't allow more background execution time for the app.
The error doesn't necessarily indicate a write request failure though, because the app may still have a big enough time window for the request and Core Data may handle the write request in the other way.
You'd likely see another error, if a write failure indeed happened. For example, if Core Data was trying to write data and the app was suspended because the background execution time ran out, you would likely see a 0xdeadlock
crash.
Best,
——
Ziqiao Chen
Worldwide Developer Relations.