We've recently upgraded to our files and Revit Server to Revit 2018.2 (from 2016). A project from two years ago has come back to life and we want to upgrade the six rvt files to 2018.2. Five of the smaller files upgraded fine but the main file refuses.
This file opens fine in 2016 but crashes when purging or auditing. Opening in 2018 has been completely unsuccessful with "Too Man Missing Elements". I was able to link this file into a new blank model fine and save it as 2018, but that is the model elements only and none of the sheets or details of the project.
What other tricks can we try to move this 2016 file to 2018?