Hey, I'd like to invite all interested in browser cache invalidation to participate in this issue: http://drupal.org/node/199946 The problem at hand is that we had Garland/Minnelli in Drupal 5 with a set of CSS and JS files, which come from the browser cache when you first hit update.php in Drupal 6, so the browser does not get the updated functionality/layout. We could add temporary measures (eg. ?core=6.x to the URL of all CSS and JS files to get them fresh in the update), but then the runtime Drupal will still suffer, because you start off with a Garland theme anyway, and the CSS/JS files with the usual URLs are not refreshed (you are asked before upgrade to switch to a core theme). Patch reviews and good ideas are welcome in the issue. Gabor