The Quick Connect 4.x databases "QC40Configuration" and "QC40ExecutionData", cannot be used in an upgrade or restore scenario as they will be overwritten.
There is currently an issue with using existing databases during a QC upgrade or QC restore.
We have logged a requirement ID of TF00130363 for 'Currently QC cleans up content of DB during setup. Customer would like to have scenario like "Use existing database" during setup.'
As a workaround, for now, back up the "QC40Configuration" and "QC40ExecutionData" and create new databases during QC install, later restore "QC40Configuration" and "QC40ExecutionData" overtop of the databases that were created during install (they have to match the database names they are overwriting).