Error Messages

This section lists descriptions and background for common error messages and warnings raised or emitted by Optuna Dashboard.

Warning Messages

Human-in-the-loop optimization will not work with _CachedStorage in Optuna prior to v3.2.

This warning occurs when the storage object associated with the Optuna Study is of the _CachedStorage class.

When using RDBStorage with Optuna, it is implicitly wrapped with the _CachedStorage class for performance improvement. However, there is a bug in the _CachedStorage class that prevents Optuna from synchronizing the latest Trial information. This bug is not a problem for the general use case of Optuna, but it is critical for human-in-the-loop optimization.

If you are using a version prior to v3.2, please upgrade to v3.2 or later, use another storage classes, or use a following dirty hack to unwrap _CachedStorage class.

if isinstance(study._storage, optuna.storages._CachedStorage):
    study._storage = study._storage._backend

set_objective_names() function is deprecated. Please use study.set_metric_names() instead.

set_objective_names() function has been ported to Optuna. Please use study.set_metric_names() function instead.

Deprecated APIs

Corresponding Active APIs

optuna_dashboard.set_objective_names(study, ["objective 1", "objective 2"])

study.set_metric_names(["objective 1", "objective 2"])