I have seen this problem a few times recently; too many elements missing. I will share the most recent situation and a related Autodesk Knowledge Network (AKN) post.
A Revit 2017 architectural model started acting up. Various error messages and crashes were occurring for multiple designers. When we would try to run Audit, we would get the error "too many elements missing". Because of this error, we could not upgrade the model to 2018 either.
I started a support case with Cad Technology Center (CTC), they...
sell our electrical package and are our Autodesk re-seller. They have a great support team, who quickly came back with this solution:
After opening the problem families with Audit and loading them back into the project, all was well. Thanks CTC Support!
Autodesk recently posted this related, and important, article on AKN: Many missing elements in Revit 2017 model.
So, be sure to apply the updates for Revit 2017 and 2018 to avoid these and other issues.
A Revit 2017 architectural model started acting up. Various error messages and crashes were occurring for multiple designers. When we would try to run Audit, we would get the error "too many elements missing". Because of this error, we could not upgrade the model to 2018 either.
I started a support case with Cad Technology Center (CTC), they...
sell our electrical package and are our Autodesk re-seller. They have a great support team, who quickly came back with this solution:
"I was able to use our "Family Exporter" tool in our BIM Batch Suite to find 3 corrupted families in the project. Once I deleted those families from the project, I was able to Audit the file.
Attached is two images showing the 3 families and how many "Instances" there are in the project. (one example iamge shown below - DJS)
What you'll need to do it "Audit" those families outside of the project and then load them into the project to repair them. If you don't have a saved copy of those families outside the project then I'm sorry, but those will have to be replaced in the family with something else and then purged from the project.
Let me know if that works for you or still have issues after replacing or "Repairing" them from the audit."
Autodesk recently posted this related, and important, article on AKN: Many missing elements in Revit 2017 model.
"Users reported that: when opening a Revit 2017 model the following error is received: The model {filename}.rvt is missing many elements, and it cannot be opened."
So, be sure to apply the updates for Revit 2017 and 2018 to avoid these and other issues.