There was never any question of guilt. But it must be clear that you have received the annual subscription from customers and that they cannot use the value. That it was not your fault is well known. However, that is not the customer's problem. The customer has paid for a service and now does not receive the equivalent value.
Therefore, it should be your task to compensate the customer in some way.
A discounted annual subscription would have been one possibility.
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@Th3G4m3r How can we discount the annual subscription of a new app for users of an old app, if there's currently no way for us to programmatically check with the new app if the old app has a non-expired sub? It's impossible without being able to push out a software update for Tweetbot. This is what we have asked Apple to allow us to do, but they haven’t given us approval yet. So we are trying to do the right thing, but we do not control the App Store. Everything has to go through Apple.