Regarding the error message, it appears that the error is quite rare. It has been reported on average a couple of times a year. And unfortunately, each time the customer rebuilt the project. Different line numbers and positions are reported in each case so it looks like a random copy/write error. For the error message as above it is reporting a problem with line 1 position 1, which suggests that the whole file has been corrupted. If this error happens too often then contact your ANSYS Support to investigate further and narrow down the issue.