We would need specific data to be able to see what is going on with the files you tried to save. If it is something you can send to technical support, or PM it to me here on the forum, I could take a look at it.
If it is not a particular file, if you can make a new empty board and it throws an error when trying to save it, then I would first recommend resetting your preferences, maybe something went wrong with them in the OS update, or the test build.