E-PE0000 — Invalid internal expression reference

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

Message

Invalid internal expression reference (node id `{...}`).

The serialized model is corrupted or was produced by an incompatible JijModeling version.

Cause

While deserializing, JijModeling encountered an internal expression node id that does not point to any node in the serialized expression table. This means the bytes are corrupted, were truncated, or were produced by a JijModeling version whose serialization format is incompatible with the one you are using.

Fix

Re-export the model with the same (or a compatible) JijModeling version as the one used to load it, and make sure the bytes are transferred and stored without modification (e.g. binary mode, no re-encoding). If the source model is available, serialize it again with your current JijModeling installation.