Improve error messages in middleware

**Feature request**
It would be great to have backup for models.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_backup` with default `false`.

Start by locating the middleware configuration entry point and how models are handled. Define the expected behavior for the new enable_backup option, including its default false value and what backup means for production deployments. The work is done when that behavior is implemented and verified with relevant tests.

Written by the indexing model from the issue text.