This means that no trial completed successfully. This almost always means that there is a bug in the objective function, and every invocation is resulting in an error. See the error output in the logs for details. In Databricks, the underlying error is surfaced for easier debugging.

It can also arise if the model fitting process is not prepared to deal with missing / NaN values, and is always returning a NaN loss.

https://databricks.com/blog/2021/04/15/how-not-to-tune-your-model-with-hyperopt.html