I have faced the similar issue. still didn't find the right solution. In my case, the below is the error trace i found from service logs. Not sure where the issue could be

"An error occurred while loading the model. You haven't configured the CLI yet! Please configure by entering `/opt/conda/envs/mlflow-env/bin/gunicorn configure`."

These are the few things i have tried after did some research.

• Make sure the cluster ML compatible DBR, i used the 13.3.
• Added all the libraries which required to the cluster directly in the cluster configuration.
• Pip dependencies has been logged with the langchain model.
• Tried to manually point out mlflow env in cluster configuration as per some of the blogs, but the UI is not showing the options like that.
• Tried different compute combinations of end point configurations.
• Configured the databricks CLI inside the cluster and make sure it has setup properly