I have recently upgraded a couple of sites to D3 v7.4.5 and, once live,
encountered remote file system errors with file writes or deletes.

The problem seemd to be an update to the way indices are handled, but the
upgrade routine has not removed the old index pointer from the data section
pointer.

If anyone comes up against this problem, just get rid of the index pointers
from the DICT FILENAME item and regenerate the indices manually. The new
CREATE-INDEX verb validates the syntax correctly.