Hello Flavio,
Good day!
Do you have any updates with regards to this? Are you able to solve your issue with schema?
I also have a theory that has something to do with network errors.
We are also having issues with regards to this after we have upgraded the server and the client to 5.0.
Some users on other department can access the server via their authoring tool(client tool) succesfully.
however on some level/department, they cannot. Once they open the file, they will be prompted with an error: "This file cannot be opened because it does not match the scheme/schema".
Hope I get a reply from you asap.