When a process variable is initially created as one type (e.g. NullType), and subsequently updated to SerializableType the ACT_FK_VAR_BYTEARRAY constraint is violated.
For us, this could have quite a large impact as I can think of a few scenarios where this could occur, the main one being a variable initialised or passed in as null and then updated with a value later.
This was introduced in the fix for as previously the variable was deleted and recreated, however now the code attempts to change the type.
This results in a ByteArrayRef being created, but this is added to the DBSqlSession after the existing variable creation causing the constraint violation.