are you working off a Central file on a network server or are you using Revit Server in your Network?
the "incorrect schema" message relates to a disconnect of network resources.
the simple solution is:
discuss with the entire team.
IF-
Model A is good do nothing
Model E is bad find the latest
Model FP is good do nothing
Model M is good do nothing
confirm all users are out of all revit models (linked or otherwise)
find the latest valid local file - confirm with all users.
Model E is bad - find whomever has the latest valid Local file have them save and sync to central and relinquish all and close the local file.
depending on access to the Network (creating files rights & permissions) have someone who can open and detach from central (preserve worksets)
this will give you the opportunity to create new Central model to correct the issue.
once the new central file has been reestablished on your network all users are encouraged to create a new Local file and overwrite the previous one.
if you have multiple users working in 1 model and each has done considerable amounts of work that has not been saved back to the central file, then each user can open THEIR LOCAL FILE DETACH from central, to create a dummy file and transfer their work to the new VALID central file.
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If a solution is provided by any posters please mark them as Solved to benefit everyone else.
thank you