P.S. Possibly something to do with my WordPress being installed in a subfolder (e.g., http://www.xxx.com/blog/.htaccess) while WP Fast Cache looks for a writable .htaccess in the root directory (www.xxx.com/.htaccess)?
Following a clue in a previous post, I turned on Permalinks (was the default) and discovered that WordPress wants .htaccess in the subfolder. Deleted and re-installed WP Fast Cache, then made sure the new .htaccess code is in both places. The “file not found” error now disappears, BUT the cached files are not being served (tested by altering the contents of a cached index.html file).
