What are all these .xac and .log files filling up my directory?
These are backup data files (“.xac”) and log files (“.log”) that GnuCash creates to prevent data loss. Gnucash will remove them after a configurable amount of time (Preferences/General/”Days to retain log files”). In the normal case when your data file is ok and you don’t need old versions of the file, you can remove these files safely.