Hi @Anonymous,
Welcome to the community! 
Did you load the default Revit Content when you installed Revit?
The default installation locations for the Libraries can be found under:
Revit 2016: C:\ProgramData\Autodesk\RVT 2016\Libraries
Revit 2017: C:\ProgramData\Autodesk\RVT 2017\Libraries
It might be that someone moved your default Library Location.
To see if it installed, go to Uninstall a Program to see if it actually installed:

OR
Are you trying to load an - e.g. Door Family Type which was possibly upgraded to a later Revit Version and now you are prompted with an error message?
I hope this helps! 
Rudi Roux
MSc | Digital Engineering Manager
LinkedIn
Revit Mechanical & Electrical Systems 2018 Certified Professional | Revit MEP & Architecture 2015 Certified Professional
AutoCAD 2015 Certified Professional | Autodesk Building Performance Analysis (BPA) Certificate
If this post resolved your issue, kindly Accept as the Solution below. Kudos are always welcome ⇘