[Upgrade to Fury 0.5] class org.apache.fury.serializer.UnexistedClassSerializers$UnexistedSkipClass cannot be cast to class

[cdxf]

[Upgrade to Fury 0.5] class org.apache.fury.serializer.UnexistedClassSerializers$UnexistedSkipClass cannot be cast to class

[chaokunyang]

Hi @cdxf , thanks for reporting this issue. It seems that you use newer version of Fury to deserialize data from old version Fury. Fury read a class id for UnexistedSkipClass, so it throw such exception.

Fury registered UnexistedSkipClass

incubator-fury/java/fury-core/src/main/java/org/apache/fury/resolver/ClassResolver.java

Line 349 in 48361cb

register(UnexistedSkipClass.class);

This registered class id may be used by other class in older Fury, it's possible to read it as UnexistedSkipClass, which is the error you see. I can submit a PR to skip register UnexistedSkipClass, but if you use newer Fury to deserialize older Fury, you will still see other strange error. Currently we didn' provide binary compatibility. Such compatibility will be provided in the future, but not now. Could you try https://fury.apache.org/docs/guide/java_object_graph_guide#upgrade-fury to upgrade Fury?