E-PE0005 — Serialized problem has no objective function

Error Type	Protobuf Error
Phase	loading a model via protobuf (from_protobuf)
Python exception	jijmodeling.ProtobufError

Message

The serialized problem has no objective function

Cause

The serialized Problem message has no objective field. JijModeling’s to_protobuf always writes an objective (a problem’s objective defaults to the constant 0), so this error means the bytes were produced by external tooling that omitted the field, or were corrupted in transit.

Fix

If the bytes come from external tooling, always emit the objective field — a constant 0 expression is fine. Otherwise verify the bytes are exactly what to_protobuf produced (binary-safe transfer, no truncation) and re-export the model from the source.