The code invoked by the IndexManager >> usageReport method calls PositionableStream >> nextWord. However, nextWord is implemented only in the legacy stream collections (PositionableStreamLegacy and subclasses), not in the portable streams (PositionableStreamPortable and subclasses). So in a system in which Portable Streams are installed, IndexManager >> usageReport encountered an MNU.
Systems that originate in versions earlier than 3.0 will have portable streams installed by default.
Last updated: 12/16/15