“The requested snapshot version is too old.” error in Firestore

问题

While using Swift client for firebase, starting Feb 09, I started to see the error message "The requested snapshot version is too old." in the callback of addSnapshotListener.

What does that error mean?

How can I fix it?

Thanks!

来源：https://stackoverflow.com/questions/60175102/the-requested-snapshot-version-is-too-old-error-in-firestore