If you open a model that contains one or more Revit links, a message displays if a linked model needs to be upgraded to the current software release.
The message indicates the software release of the model and the release to which it will be upgraded. Depending on the size of the model, the upgrade process can take some time.
The upgrade changes to a linked model are temporary; they are not saved when you save the host model.
To permanently upgrade a linked model, you must close the host model and then open, upgrade, and save the linked model. The next time that you open the host model, the linked model will not require an upgrade.