The DB Explorer cannot be opened after schema package renaming of entity types because it seems that deprecated entity types which are removed from our java project break the database. In the database the entity types and deprecated entity types can be part of the identical package. The schema update tries to rename the package name for entity types and deprecated entity types and then the database is broken for the DB Explorer.
If I remove the deprecated entity types from the database manually before the schema update then the database can be opened in the DB Explorer after the schema update.
ObjectDB Version: 2.8.5.b05