Github user tzulitai commented on the issue:
https://github.com/apache/flink/pull/5950
I think even with the `UnloadableTypeSerializerException` exception
bubbling approach, we actually still need a flag in the serialization proxy to
decide how to handle the exception.
The serialization proxy handles deserialization of all meta data of all
registered key states, so that would be the highest level where we need to
decide whether or not to use the dummy serializer.
If we want to hand out this control to an even higher level (i.e. the
backend), we would then need to break up the deserialization logic from the
serialization proxy, which IMO isn't appropriate.
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