Error message - "Too Many Missing Elements

[Anonymous]

 Hi everyone, I would need help to restore a model that has the error in the opening "missing elements". With the audit the model is not loaded, with detach yes. The version is 2017.2. The problem is with I can not upgrade to the next 2018 and 2019 versions for the same reason "missing elements". If anyone can help me, I thank him very much

[barthbradley]

Any more information provided through the warning dialog box?  Can you Expand it to see the specifics?  

[SteveKStafford]

Review this DOCUMENT. Short answer: need to recreate a central file from an older local file that you can still open, or older version of the central file (backup) that opens.

Make sure everyone is using the latest build of Revit. Don't mix Window operating systems (win 7 and win 10 for example)...and the other advice in the article, for example it sometimes is caused by family corruption. You can try to use Save Library and see if that crashes on any specific families.